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f\o^ O 



Bulletin of 
The Natural Histoi 
Museum 




Zoology Series 




VOLUME 61 NUMBER 2 30 NOVEMBER 1995 



The Bulletin of The Natural History Museum (formerly: Bulletin of the British Museum 
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World List abbreviation: Bull. nat. Hist. Mus. Lond. (Zool.) 
© The Natural History Museum, 1995 



Zoology Series 
ISSN 0968-0470 Vol. 61, No. 2, pp. 91-138 

The Natural History Museum 

Cromwell Road 

London SW7 5BD Issued 30 November 1995 

Typeset by Ann Buchan (Typesetters), Middlesex 
Printed in Great Britain at The Alden Press, Oxford 



Bull. nat. Hist. Mus. Lond. (Zool.) 61(2): 91-101 



TH J HAL 



12 DEC 1995 

Preliminary studies on a mandibulohyoid h ucmc0 
ligament' and other intrabuccal connecti\|f oolqqyubrar\ 
tissue linkages in cirrhitid, latrid and 
cheilodactylid fishes (Perciformes : 
Cirrhitoidei) 



PETER HUMPHRY GREENWOOD* 

Visiting Research Fellow, The Natural History Museum, Cromwell Road, London SW7 5BD and 
Honorary Research Fellow, J.L.B. Smith Institute of Ichthyology, Private Bag 1015, Grahamstown, 
6140 South Africa 



CONTENTS 



Introduction 91 

Material and Methods 92 

Ligamentous and other connective tissue linkages between the mandible, the palatoquadrate, the hyoid arch 

and the opercular series in three cirrhitoid families 93 

The family Cirrhitidae 93 

The family Latridae 93 

The family Cheilodactylidae 97 

Discussion and Conclusions 98 

Acknowledgements 100 

References 101 



Synopsis. In certain taxa of at least three groups of percomorph fishes belonging to the cirrhitoid families 
Cirrhitidae and Latridae, there is a connective tissue linkage between the mandible and the hyoid arch, suggestive of 
the mandibulohyoid ligament described in certain sub-percomorph groups. This ligament is generally thought to be a 
feature of lower teleost fishes, although a mandibulohyoid connection has also been identified in a few more derived 
taxa. The mandibulohyoid connection in the Cirrhitidae examined would appear to originate from the tendinous 
aponeurosis associated with the Aw division of the adductor mandibulae muscles, but its derivation in the latrid 
species Acantholatris monodactylus remains undetermined. The Aw aponeurosis in A. monodactylus, as well as in 
the latrid Mendosoma, and in two genera of Cheilodactylidae (viz. Chirodactylus and Cheilodactylus) ramifies 
extensively over the paladoquadrate arch and part of the opercular series. This system, together with various 
intrabuccal ligaments is described from representatives of the three cirrhitoid families studied. 

It is concluded that, contrary to several earlier ideas, a mandibulohyoid linkage is of taxonomically and 
phylogenetically widespread occurrence in teleosts but that it might be derived from different connective tissue 
sources. The value of this connective tissue complex in phylogenetic studies has yet to be established, but it appears 
to be of use in at least establishing intragroup relationships within the Cirrhitoidei. 



INTRODUCTION 



A recent anatomical study of certain cirrhitoid fishes (sensu 
Greenwood, 1995) has revealed a number of markedly differ- 
ent ligament and tendon systems which separately or con- 
jointly link the mandible with the hyoid arch, the 
palatoquadrate arch and the opercular series. Some of these 
connections have a degree of complexity not previously 
recorded among teleost fishes. 
Of particular functional interest are the two types of direct 



t Dr Greenwood died 3 March 1995. 
©The Natural History Museum, 1995 



and ligament-like connections between the ceratohyal and 
mandible in some cirrhitid species, and a third type found in 
one of the latrid species examined (family placement after 
Greenwood, 1995). These linkages invite comparison with 
the so-called mandibulohyoid ligament generally thought to 
be commoner in lower teleosts than in perciform taxa, or 
even restricted to the former groups (see Verraes, 1977; 
Lauder & Liem, 1980; Lauder, 1982; but see also Osse, 1969, 
Springer et al, 1977, and Aerts et ai, 1987 for certain 
perciforms, and Anker, 1974, for gasterosteiforms). A man- 
dibulohyoid ligament also occurs in the semionotiform lepi- 
sosteids Lepisosteus and Atractosteus (Wiley, 1976). 



gfl\i ^M;^ 



92 



PH. GREENWOOD 



The nature of the hyoid-mandibular connection in the 
cirrhitoids, a derived percomorph group (Greenwood, 1995), 
and that described in other teleosts and in the Lepisosteidae, 
raises doubts about the strict homology of the connection in 
these various taxa. 

Functionally, it would seem that a mandibulohyoid connec- 
tion is of importance both in adults (see Aerts et al. , 1987) 
and in early larval stages (Verraes, 1977); its phylogenetic 
history in this context is discussed at length by Lauder (1982). 

Regrettably, the feeding studies on cirrhitoids, from which 
this anatomical study arose, are not sufficiently advanced or 
refined to allow informed speculation on any correlation 
between the morphology and the feeding habits of these 
fishes. Furthermore, many other cirrhitoid taxa remain to be 
studied before it will be possible to evaluate what significance 
the different types of intragroup mandibulohyoid and other 
linkages (or absence thereof) may have in unravelling the 
taxonomy and phyletic relationships of the group. Neverthe- 
less, there are indications from this study, and from informa- 
tion in the literature on various forms of mandibulohyoid 
connections, that further investigations may yield insight into 
the biomechanics of feeding and into historical relationships. 



MATERIALS AND METHODS 



Material 

Clupeidae: 
Salmonidae: 
Characidae: 
Cirrhitidae: 



Etrumeus terres. RUSI 34140 (1 speci- 
men) 

Oncorhynchus mykiss RUSI 36417 (3 

specimens) 

Hydrocynus vittatus RUSI 19355 (1 

specimen) 

Amblycirrhitus bimacula RUSI 77-20 (3 

specimens) 

Cirrhitichthys oxycephalus RUSI 40526 

(3 specimens) 

Cirrhitops fasciatus RUSI 2375 (1 speci- 
men; ex Hawaii) 

Cyprinocirrhites polyactis RUSI 12339 

(3 specimens) 

Paracirrhites arcatus RUSI 30975 (2 

specimens) 

Paracirrhites forsteri RUSI 39419 (3 

specimens) 

Acantholatris monodactylus RUSI 

33485 (2 specimens) 

Mendosoma lineatum 

RUSI 33613 (1 specimen) 
RUSI 33626 (1 specimen) 
RUSI 26176(1 specimen) 

Cheilodactylus fasciatus DIFS unreg. (2 

specimens) 

Cheilodactylus pixi DIFS unreg. (3 

specimens) 

Chirodactylus brachydactylus DIFS 

unreg. (3 specimens) 

DIFS: Department of Ichthyology and Fisheries Science, 
Rhodes University, Grahamstown. RUSI: J.L.B. Smith Insti- 
tute of Ichthyology, Grahamstown. 



Latridae: 



Cheilodactylidae: 



Method 

The entire opercular series, palatopterygoid arch and hyoid 
arch of one side, together with the mandible, premaxilla and 
maxilla of that side, were dissected away from the head. 
Muscles, tendons and ligaments were examined on the dis- 
sected side, and checked on the contralateral aspect which 
was left in situ. 

All specimens had been fixed in formalin and preserved in 
either ethyl or propyl alcohol. 

In the absence of ontogenetical information on the devel- 
opment of ligamentous and tendinous systems in these fishes, 
ligaments and tendons in the various taxa are presumed to be 
homologous if their places of origin and insertion are similar. 



ABBREVIATIONS FOR FIGURES 

Abbreviations for tendons and ligaments are given separately 
with each figure. 

Muscles: 

Add. mand. 

I u & m: Adductor mandibulae Aj upper and main divi- 
sions respectively 

Aw: Aw division of adductor mandibulae muscle 

Awt: Tendinous aponeurosis of adductor mandibulae 

Aw 

Geh: Geniohyoideus 

Im: Intermandibularis 

St: Sternohyoideus 






Skeletal elements: 



Ang: 


Anguloarticular 


Bb: 


1st basibranchial 


Ch: 


Ceratohyal 


Dt: 


Dentary 


Ect: 


Ectopterygoid 


Ent: 


Entopterygoid 


Epi: 


Epihyal 


F: 


Raised facet for articulation with epihyal 


Ga: 


Gill arch 


Hyom: 


Hyomandibula 


Hyp: 


Hypohyals 


Ihyl: 


Interhyal 


lop: 


Interoperculum 


Max: 


Maxilla 


Mt: 


Metapterygoid 


Pal: 


Palatine 


Pop: 


Preoperculum 


Q: 


Quadrate 


R: 


Retroarticular 


Sy: 


Symplectic 


V: 


Vomer 



MANDIBULOHYOID CONNECTION IN CIRRHITOID FISHES 



93 



LIGAMENTOUS AND OTHER CONNECTIVE 
TISSUE LINKAGES BETWEEN THE 
MANDIBLE, THE PALATOQUADRATE, THE 
HYOID ARCH, AND THE OPERULAR SERIES 
IN THREE CIRRHITOID FAMILIES 



The family Cirrhitidae 

On the basis of their mandibulohyoid connections, two 
distinct groups can be recognised within the cirrhitid species 
examined. A third group, represented by Amblycirrhitus 
bimacula (Jenkins), has no macroscopically detectable man- 
dibulohyoid linkage (see below). 

Group I species (viz. Cyprinocirrhites polyactis [Bleeker], 
Cirrhitichthys oxycephalus [Bleeker] and Cirrhitops fasciatus 
[Bennett] have a stout, ligament-like connection between the 
ceratohyal of each side and the coronoid process of the 
corresponding dentary ramus (Fig. 1A). Group II species 
(viz. Paracirrhites arcatus [Cuvier] and P. forsteri [Schneider] 
also have a ligament-like band of tissue stemming from the 
lateral aspect of each ceratohyal, but here it links each hyoid 
arch with, predominantly, the corresponding quadrate, on 
which it inserts immediately above that bone's process for 
articulation with the anguloarticular. Part of this tissue, 
however, is apparently continous with the tendinous insertion 
of the Aw division of the adductor mandibulae muscle, (Fig. 
1C). There is no macroscopically obvious and clearly defined 
connective tissue linkage between the mandible and hyoid 
arch in Amblycirrhitus bimacula (hereafter referred to as 
Group III). 

In all three groups the adductor mandibulae Aw division 
originates on the quadrate through a posterior extension of 
the muscle's tendinous central aponeurosis, and thus is of the 
basic perciform type as defined by Gosline (1986). The 
extension is well-demarcated and moderately deep, and lies 
across the quadrate-anguloarticular joint. Amblycirrhitus 
bimacula (the single Group III species examined) is excep- 
tional in this respect because the tendon lies very slightly 
above the jaw articulation. Members of all three groups have 
the fascia covering the Aw muscle extending posteriorly onto 
the lower half of the quadrate, part of the preoperculum, and 
the upper margin of the interoperculum as well. 

Within the three species of Group I there are differences in 
the association between the mandibulohyoid connection and 
the tendon of the adductor mandibulae A x muscle inserting 
on the maxilla. Cyprinocirrhites polyactis is unique in having 
what appears to be a short branch of the mandibulohyoid 
connection arising near the latter's attachment to the coro- 
noid process of the dentary and then joining the maxillary 
tendon of the adductor mandibulae A Y muscle (Fig. 1A). In 
Cirrhitichthys oxycephalus and Cirrhitops fasciatus , the maxil- 
! lary tendon partially fuses with the mandibulohyoid connec- 
i tion at the point where the two cross over each other (the 
latter lying medial to the maxillary tendon). From the point 
i of fusion a short section (interpreted as a continuation of the 
, maxillary tendon) runs into the tendinous central aponeurosis 
of the adductor mandibulae Aw muscle (Fig. IB). 

There are also intergroup differences in other ligamentous 

land tendinous linkages (Fig. 1). Species of Groups I and III 

have a small upper, anterior division of the adductor man- 

[dibulae muscle A! inserting onto the maxilla only via the 

ligamentum primordium. Group II species, in contrast, have 



that division of the muscle inserting on the maxilla through 
both the ligamentum primordium and the maxillary ligament 
of adductor mandibulae Aj muscle. In all three groups the 
major (ie lower) division of the muscle is attached to the 
ligamentum primordium and the maxillary ligament, the 
latter inserting on the ventral aspect of the maxilla, and the 
former on the bone's dorsolateral aspect. 

Other intergroup differences involve the epihyal- 
interopercular and the interhyal-interopercular ligaments 
(For comparison of these and other ligaments with the 
situation in other cirrhitoid families, see pp. 94 and pp. 97-98 
and Figs 2-4). Group II species have the latter ligament 
partly associated with the epihyal as well as the interhyal, as 
does the single Group III species dissected; in Group I taxa, 
however, the ligament is confined to the interhyal. The 
epihyal-interopercular ligament shows more marked inter- 
group differences, especially when species of Group I are 
compared with those of the other two groups, a difference 
possibly associated with the manner in which the epihyal 
contacts the interoperculum. In Group II taxa, the lateral 
face of the epihyal head articulates with a well-defined, 
prominently raised and posteriorly directed facet situated a 
little below the dorsal margin of the interoperculum and 
slightly behind the bone's midpoint. The epihyal- 
interopercular ligament in these fishes is short and stout, 
originates on the lateral face of the epihyal near its dorsal tip, 
and runs forward at approximately 45 to the sagital plane. It 
inserts on the upper and anterior faces of the prominence 
supporting the facet on the interoperculum against which the 
epihyal articulates. A similar epihyal-interopercular ligament 
occurs in the single Group III species examined, viz. Ambly- 
cirrhitus bimacula. However, in this species, unlike those of 
Group II, the interopercular facet is located on a relatively 
lower base. 

The epihyal-interopercular ligament is most distinctive in 
Group II. In species of this group (unlike the other groups) 
the epihyal articulates directly with the medial face of the 
interoperculum and not with a facet carried on a distinct and 
elevated base (albeit only slightly so in the single Group III 
species examined). The ligament itself is a prominent feature 
originating (as in other groups) on the dorsal tip of the 
epihyal's lateral face, from which it runs anteriorly onto the 
dorsal margin of the interoperculum at a point near the 
bone's anterior tip, where it is narrowly separated from the 
attachment point of the mandibulo-interopercular ligament 
(cf. Acantholatris monodactylus Fig. 3 & p. 94). 

A short interhyal-metapterygoid ligament is present in all 
three groups. 

No interhyal-preopercular ligament is present in any exam- 
ined species of the three groups (cf. the other cirrhitoids 
described below). 

A stout mandibulo-interopercular ligament (Fig. 1C; lig. 3) 
is present in taxa of the three groups. It is confined to the 
lateral face of both elements in all species except Cyprinocir- 
rhites polyactis and Cirrhitichthys oxycephalus (both members 
of Group I). In these two species it divides anteriorly to insert 
on both the lateral and the medial aspects of the anguloarticu- 
lar bone. 

Also common to species of the three groups is a short and 
deep, ventrally located ligament connecting the anguloarticu- 
lar and dentary. 



94 



PH. GREENWOOD 



The family Latridae 

There are clear-cut differences in certain aspects of the 
ligamentous and other connective systems in the two latrid 
species examined, namely the monotypic genus Mendosoma 
lineatum (Gay) and the species Acantholatris monodactylus 
(Carmichael) of that polytypic genus. Also, an upper division 
of the adductor mandibulae muscle A x is absent in A. 
monodactylus whereas in Mendosoma it is an elongate, rather 
thin element which lies lateral to the major part of the muscle 
and extends over the greater part of its length. The minor 
division, unlike the major one, has no direct connection with 
the ligamentum primordium and inserts on the maxilla, 
together with the major division, via the maxillary tendon of 
the A, muscle. 

In Mendosoma the adductor mandibulae Aw division is a 
very thin muscle, largely tendinous and with a single posterior 
extension of its tendinous aponeurosis. This runs slightly 
below the upper point of the articulation of the lower jaw 
with the quadrate, to which bone it is attached a short 
distance from the anterior border (Fig. 2; tendon 3). In other 
words, it is of the basic percomorph type sensu Gosline 
(1986), except that in Mendosoma it has one prolongation 
extending along the symplectic, another running ventrally to 
attach to the medial aspect of the preoperculum, a third, 
directed dorsally to insert on the quadrate, and a fourth 
directed obliquely backwards to attach to the ventral aspect 
of the interoperculum medially and anteriorly. 

In all essentials, the adductor mandibulae Aw tendon 
system's extension onto the interoperculum and preopercu- 
lum in Mendosoma is very similar to that in Acantholatris, 
with that in Mendosoma, as it were, foreshadowing the more 
clearly differentiated condition in Acantholatris (cf. Figs 2 & 
3). 

There is no ligament-like connection between the mandible 
and hyoid arch in Mendosoma (cf. Acantholatris; Fig. 3). 

The epihyal-interopercular ligament is stout and short, 
connecting the lateral aspect of the epihyal with the dorsal 
margin of the interoperculum a short distance anterior to its 
slightly raised facet for articulation with the epihyal. Unlike 
the backward-facing facet in those cirrhitids in which it 
occurs, that in M. lineatum faces forward (Fig. 2), as it does in 
the other latrid examined (Acantholatris monodactylus; and 
in the cheilodactylids dissected). 

A discrete interhyal-interopercular ligament (present in 
cirrhitids) is apparently lacking in M. lineatum (as it is also in 
Acantholatris, and Cheilodactylus) . 

Like the two latter genera, but not in the cirrhitids exam- 
ined, Mendosoma has a well-developed interhyal- 
preopercular ligament and another, more dorsally placed 
ligament between the interhyal and the metapterygoid (Fig. 



2; lig. 7). This latter ligament I consider to be the homologue 
of the interhyal-quadrate ligament in Cheilodactylus, and the 
ligament in Acantholatris which runs from the interhyal to 
both the quadrate and the entopterygoid (see p. 98 & p. 99 
respectively). 

Mendosoma has discrete lateral and medial divisions of the 
mandibulo-interopercular ligament, with the medial division 
terminating a short distance behind the anterior tip of the 
interoperculum (Fig. 2; lig. 6), and the lateral division 
extending much further posteriorly. 

The anguloarticular-dentary ligament is short and stout, 
markedly stouter than in any cirrhitid species examined, and 
stouter than that in Acantholatris. 

As compared with the ligamentous and other connective 
tissue systems in Mendosoma lineatum, those in Acantholatris 
monodactylus are considerably more complex, (as they are 
when compared with the cirrhitid species studied). As was 
noted earlier (p. 94), there is no obvious sub-division of the 
adductor mandibulae A 1 muscle in A. monodactylus. How- 
ever, anteriorly the upper third of the muscle, unlike the 
other two-thirds, is free from the ligamentum primordium 
and inserts on the maxilla only through the maxillary tendon, 
to which the major part of the muscle is also attached. 

Acantholatris monodactylus has a substantial Aw portion of 
the adductor mandibulae muscle. From the muscle's 
mediolateral tendinous aponeurosis a stout and relatively 
short branch (tendon 3 in Fig. 3) runs posteriorly to insert on 
the anteromedial aspect of the preoperculum's horizontal 
limb. 

A second stout and much longer tendon from the Aw 
muscle (tendon 5 in Fig. 3) extends from the ventral margin 
of the muscle above the anguloarticular bone, and runs 
obliquely backwards to attach to the medial aspect of the 
interoperculum a short distance from that bone's anterior tip. 
This tendon, unlike tendon 3, is not derived from the 
aponeurosis of the adductor mandibulae Aw muscle but 
originates directly from the muscle itself. Immediately after 
its origin, tendon 5 is attached to the anterodorsal aspect of 
the anguloarticular's medial face. It then passes over that face 
of the retroarticular, and attaches to the medial aspect of the 
interoperculum a short distance from the bone's anterior tip. 
Since this tendon links the mandible with the interoperculum 
it would appear to be the functional equivalent of the 
mandibulo-interopercular ligament in the other species 
described above. However, a true and very long mandibulo- 
interopercular ligament is also present in A. monodactylus 
(Fig. 3; lig. 6). Anteriorly it has an extensive attachment to 
the lateral face of the anguloarticular and retroarticular 
bones, as well as another on the posterior face of the 
retroarticular. From here the ligament extends across to, and 



Fig. 1 A: Cyprinocirrhites polyactic (Group I species) Medial aspect of the left lower jaw, cheek region and hyoid arch, viewed obliquely 
from above, to show the mandibulohyoid connection (semi-schematic). The branchial skeleton is displaced to the right. About times natural 
size. 1 : Mandibulohyoid connection; 2a: tendon from lower part of adductor mandibulae A, muscle to maxilla; 2b: continuation of tendon 
2a, joining tendinous aponeurosis of adductor mandibulae muscle Aw. Lig. prim: Ligamentum primordium. 

B: Cirrhitops fasciatus (Group I species) Diagramatic representation of mandibulohyoid connection and related tendons; medial aspect of left 
side to demonstrate the second form of tendinous relationships within species of Group I. Abbreviations as in Fig. 1 A. 

C: Paracirrhites forsteri (Group II species). Medial aspect of the right lower jaw, cheek region and hyoid arch, viewed somewhat dorsally; the 
branchial skeleton and hyoid arch considerably displaced to the left and posteriorly in order to reveal the mandibulohyoid connection. 
(Semi-schematic). About times natural size. 1: Posterior portion of mandibulohyoid connection, inserting partly on the quadrate, and partly 
continuous with tendinous aponeurosis of the adductor mandibulae muscle Aw (Awt); 2b: ventral continuation of maxillary tendon of 
adductor mandibulae muscle A,; 3: interopercular-mandibular ligament; 4: tendon of adductor mandibulae A 2 muscle; Lig. prim: 
ligamentum primordium. 



MANDIBULOHYOID CONNECTION IN CIRRHITOID FISHES 

Lig. prim- 



95 




Lig. prim. 




96 



P.H. GREENWOOD 




Fig. 2 Mendosoma lineatum Medial aspect of left lower jaw, cheek region, and hyoid arch. Scale = 2mm. 2a: Maxillary tendon of adductor 
mandibulae muscle A^ 2b: extension of tendon 2a, joining tendinous aponeurosis of adductor mandibulae muscle Aw; 2c: tendon of 
adductor mandibulae muscle A 2 ; 3a & b: extensions of adductor mandibulae muscle Aw's tendinous aponeurosis; 6: 
interopercular-mandibular ligament; 7: interhyal-metapterygoid ligament. 



along, the dorsal and dorsolateral margins of the interopercu- 
lum, ending at a point about midway between the bone's 
anterior tip and the face of the prominent, forward-facing 
articulatory facet for the epihyal (cf pp. 94). Here it attaches 
to a slight eminence on the dorsal margin of the interopercu- 
lum. At first sight the ligament appears to be continuous with 
the epihyal-interopercular ligament (Fig. 3; lig. 4) which also 
inserts at that point. Careful dissection reveals, however, that 
the two are separate entities (see also p. 93 and p. 94 
respectively for the situation in cirrhitids and the latrid 
Mendosoma). 

Apart from the more complex condition in cheilodactylids, 
this double linkage of the mandible with the interoperculum, 
one involving both tendons and ligaments, seemingly has not 
been recorded in any other teleosts. However, it also occurs 
in Mendosoma (see p. 94 and Fig. 2) where the lowermost 
arm of the Aw aponeurosis is attached to the anteromedial 
aspect of the interoperculum, and in Cheilodactylus (see 
below, and tendon 5 in Fig. 4). 

As in Mendosoma, the anguloarticular-dentary ligament in 
A. monodactylus is short and stout. 

An elongate and broad ligament (lig. 7 in Fig. 3) connects 
the upper face of the interhyal with the quadrate and, mainly, 
with the entopterygoid. This connection is similar to that in 
Cheilodactylus (see Fig. 4, and p. 98), and, from its intercon- 
nections would appear to be homologous with the ligament 
joining the interhyal with the metapterygoid in Mendosoma 
(Fig. 2; lig. 7) and the cirrhitid species examined. 

The interhyal-interopercular ligament, present in all mem- 
bers of the Cirrhitidae examined, is absent in the latrids and 
cheilodactylids dissected. An interhyal-preopercular liga- 
ment, present in the other cirrhitoids studied except the 
cirrhitids, is also developed in Acantholatris . Here, although 



very short, it is stout and has an extensive attachment area on 
the interhyal and on the preoperculum, which it joins at the 
point where the upper, vertical arm of that bone begins to 
curve forward to form its horizontal arm. 

A feature unique to Acantholatris monodactylus amongst 
the cirrhitoid taxa examined is the presence of a well-defined 
ligament connecting the hyoid arch and the dentary, a linkage 
in no way associated with the adductor mandibulae Aw 
muscle or its aponeurotic system (see Fig. 3). Posteriorly, this 
ligament is attached to the summit of a distinct prominence 
on the anterior face of the ceratohyal and situated immedi- 
ately below the ceratohyal-epihyal suture. Anteriorly, the 
ligament inserts on the dentary conjointly with the anterior 
end of the anguloarticular-dentary ligament (see above and 
Fig. 3; lig.l). 

The family Cheilodactylidae 

The account which follows is based on dissections of Cheilo- 
dactylus fasciatus Lacepede. Since the situation is virtually 
identical in two other cheilodactylid species studied, Cheilo- 
dactylus pixi (Smith) and Chirodactylus brachydactylus 
(Cuvier), the term Cheilodactylus is used to cover all three 
taxa. What interspecific differences do exist are noted on 
page 98. 

Of all the cirrhitoid species examined, the ligament and 
tendon systems separately or conjointly linking the mandible, 
the hyoid arch, the opercular series, and the palatoquadrate 
arch in Cheilodactylus are by far the most complex. The 
greatest similarities, however, are with those systems in the 
latrid Acantholatris monodactylus (cf. Figs 3 & 4). In the 
cheilodactylids examined, and like A. monodactylus, there is 
no obvious subdivision of the adductor mandibulae Aj 



MANDIBULOHYOID CONNECTION IN CIRRHITOID FISHES 



97 




Fig. 3 Acantholatris monodactylus Medial aspect of left lower jaw, cheek region and hyoid arch. Scale = 2mm. 1: Anguloarticular-dentary 
ligament; 2a: maxillary tendon of adductor mandibulae muscle A,; 2b: extension of above tendon joining tendinous aponeurosis of 
adductor mandibulae muscle Aw; 3: tendon of Aw muscle to preoperculum; 4: epihyal-interopercular ligament; 5: tendon from Aw muscle 
to interoperculum; 6: interopercular-mandibular ligament; 7: interhyal-quadrate-entopterygoid ligament. Dashed outline that of the 
mandibulohyoid connection. 



muscle, whose insertion on the maxilla is identical with that in 
the latter taxon. 

The Aw portion of the adductor mandibulae muscle in 
Cheilodactylus is noticeably less extensive than in Acanthola- 
tris, but its tendinous connections with the interoperculum 
and the palatoquadrate arch are more complicated than in 
that taxon. Also, in Cheilodactylus the ventral extension of 
the adductor mandibulae A x maxillary tendon is noticeably 
stouter than in Acantholatris (cf. Figs 3 & 4) but, unlike 
Acantholatris , in Cheilodactylus it is derived from the medial 
and not the lateral tendinous aponeurosis of the muscle's Aw 
division. A most obvious difference between the two taxa is 
the absence of a ligament connecting the hyoid arch with the 
mandible in Cheilodactylus (cf. Figs 3 & 4). 

A somewhat tendinous section of the adductor mandibulae 

I Aw division (tendon 3 in Fig. 4) in Cheilodactylus runs 
posteriorly, becoming completely tendinous as it crosses the 
hind margin of the anguloarticular and its joint with the 
quadrate. It inserts on the anterior tip of the preoperculum 
just below that bone's dorsal margin. At a point near the 
centre of the anguloarticular this partly tendinous section of 
the Aw division of the adductor mandibulae muscle gives off 

I a ventroposteriorly directed branch which soon becomes 

, completely tendinous. The anterior part of this tendon (5a in 
Fig. 4), immediately below its point of departure from tendon 
3, is attached to the anguloarticular near its anterior margin. 
It thus lies below the bone's articulation with the quadrate. 

I The posteriad extension of tendon 5a runs backwards and 
somewhat dorsally, seemingly joining the lateral face of a 

, broad, stout, dense, and obliquely orientated ligament-like 
strap (5b in Fig. 4) extending from the midpoint of the 
quadrate to the anteroventral surface of the interoperculum. 
Together the two elements (ie 5a and 5b in Fig. 4) form a 'Y' 
shaped linkage between the anguloarticular, quadrate, and 

I interoperculum. Also, because the anterior arm of the 'Y' (ie 



5a) is associated with an extension of the Aw muscle onto the 
anguloarticular, the linkage involves that bone as well. 

Without ontogenetic information it is difficult to decide 
whether the element 5b of the 'Y' is, at it appears to be, a 
branch of the tendon 5a (and thus is itself a tendon) or 
whether it is strictly a ligament with which tendon 5a has 
fused. That none of the other cirrhitoids examined has a 
quadrato-interopercular ligament would add credence to 5b 
being a true branch of 5a, and thus representing a consider- 
able posterior extension of the Aw muscle's tendon system. 
Also, in the other cheilodactylids examined, the 'Y'-shaped 
connection gives no hint of it having originated from a tendon 
and a ligament (see below). The potential complexity and 
posterior extension of that system is clearly demonstrated in 
another percomorph, the percid Gymnocephalus cernua (L.); 
see Elshoud-Oldenhave & Osse (1976; fig. 4.1). 

When comparisons are made with the latrid Acantholatris, 
(see p. 94 and Fig. 3) it appears that the 'Y'-shaped complex 
in Cheilodactylus is, from its disposition and attachment 
points, homologous with the simple tendon (5 in Fig. 3) 
associated with the Aw portion of the adductor mandibulae 
muscle in Acantholatris. Tendon 5 in that taxon is attached to 
both the anguloarticular and the medial face of the interoper- 
culum, and is separated by a short section of Aw from tendon 
3 which inserts on the preoperculum (Fig. 3). In turn, and 
also from its disposition and points of attachment, the latter 
tendon would seem to be homologous with the longer tendon 
3 in Cheilodactylus which also inserts on the preoperculum. 
An early evolutionary stage in the development of this 
complex in both Cheilodactylus and Acantholatris may be 
represented by the tripartite posterior extension of the Aw 
aponeurosis in Mendosoma, which also serves to link the Aw 
muscle with the quadrate, preoperculum and interoperculum 
(see p. 94 and Fig. 2). 

The two other cheilodactylid species dissected, Chirodacty- 



98 



PH. GREENWOOD 




Fig. 4 Cheilodactylus fasciatus Medial aspect of left lower jaw, cheek region and hyoid arch. Scale = 2mm. 1: Anguloarticular-dentary 
ligament; 2a: maxillary tendon of adductormandibulae muscle A,; 2b: extension of above tendon joining tendinous aponeurosis of adductor 
mandibulae muscle Aw; 3: tendon of adductor mandibulae muscle Aw to preoperculum; 4: epihyal-interopercular ligament; 5a: extension 
of tendon 3; 5b: branch of tendon 5a, attaching to quadrate above and interoperculum below; 6: interopercular-mandibular ligament; 7: 
interhyal-quadrate ligament; x: anguloarticular-quadrate ligament. 



lus brachydactylus and Cheilodactylus pixi, have a 
mandibular-preopercular-quadrate tendon system essentially 
like that described above in Cheilodactylus fasciatus. In these 
species the interopercular-quadrate branch (Fig. 4; 5b) does 
not partly overlap that section of the complex (Fig. 4; 5a) 
going to the anguloarticular. Instead, the two branches meet 
in the same plane, with the result that the complex is clearly 
single and 'Y'-shaped. Since the specimens of Chirodactylus 
brachydactylus (standard length 106 mm) and Cheilodactylus 
pixi (S.L. 70-81 mm) are much smaller than the specimen of 
Cheilodactylus fasciatus (S.L. 243 mm), the difference could 
be related either to the larger size of the C. fasciatus specimen 
or to individual variation. 

The epihyal-interopercular ligament in Cheilodactylus is 
short and broad (shorter even than that in the latrid Mendo- 
soma; and unlike the long and anteriorly directed ligament in 
the other latrid examined, Acantholatris, Fig. 4; lig. 4). As in 
Acantholatris, but unlike Mendosoma, the interopercular 
facet for the epihyal in Cheilodactylus is prominent and 
well-developed (see Fig. 4). The interhyal-quadrate ligament 
is long and flat (Fig. 4; lig. 7), again like that in Acantholatris, 
but unlike its presumed homologue, the short and stout 
interhyal-metapterygoid ligament in Mendosoma. 

The interhyal-preopercular ligament in Cheilodactylus is 
also short and stout. No discrete interhyal-interopercular 



ligament is developed in the cheilodactylids, a characteristic 
shared with the two latrid genera examined, but not with the 
cirrhitid species studied. 

A stout anguloarticular-dentary ligament is present, as it is 
in the other cirrhitoids, but unlike those taxa Cheilodactylus 
has a short and broad ligament (x in Fig. 4) connecting the 
uppermost part of the anguloarticular's posteromedial face to 
the quadrate, where it is attached to the ventral rim of that 
bone's facet for articulation with the anguloarticular. This 
small ligament, not found in any of the other cirrhitoids 
examined, is almost entirely hidden by tendon 5a of the 'Y' 
shaped complex described above. 

A very stout interopercular-mandibular ligament originates 
laterally on the dorsal margin of the interoperculum near its 
anterior tip, and inserts mostly on the lateral aspect of the 
anguloarticular and retroarticular bones, but with a short 
medial branch going to the posteromedial face of the retroar- 
ticular (6 in Fig. 4). 



DISCUSSION AND CONCLUSIONS 



The taxonomically and phylogenetically widespread occur- 



MANDIBULOHYOID CONNECTION IN CIRRHITOID FISHES 



99 



rence of a mandibulohyoid linkage in bony fishes (see Tcher- 
navin, 1953, and references cited by Verraes, 1977, Springer 
et al., 1877, Lauder & Liem, 1980, and above) certainly 
seems to support the views of functional anatomists with 
regard to its involvement in the mechanics of jaw opening. It 
also refutes the apparently widespread view (see reviews in 
Lauder & Liem, 1980; Lauder, 1982) that the linkage may be 
a primitive character of neopterygian fishes, one lost in 
higher teleosts (but see also Lauder & Liem, 1989, for later 
views). However, although the mandibulohyoid connection 
may be functionally homologous in both 'higher' and 'lower' 
bony fishes, there are indications that it may not be homolo- 
gous in an ontogenetical and hence phylogenetic context (see 
below). Nevertheless, the diversity of mandibulohyoid con- 
nections already known in but a few teleost fishes strongly 
suggests that the structural, functional and ontogenetic 
aspects of this system need to be reevaluated. 

Any attempt to establish or refute the homology of man- 
dibulohyoid connections in cirrhitoid fishes with those in 
other bony fish groups (see below) is hampered by a lack of 
information on the ontogeny of the linkage in the various taxa 
involved. Indeed, this problem also arises with the different 
mandibulohyoid linkages found within the cirrhitoids them- 
selves, namely those in the Cirrhitidae (p. 93) and that in the 
latrid Acantholatris monodactylus (p. 97). 

The cirrhitid linkage type in the Paracirrhites species 
examined (p. 93) strongly suggests that the connection 
between the mandible and the ceratohyal in these fishes is 
derived from an extension of the central aponeurosis of the 
adductor mandibulae muscle's Aw portion onto the hyoid 
arch (with, in addition, a partial insertion on the quadrate; 
Fig. 1C and p. 93). In another cirrhitid group (viz. Cyp- 
rinocirrhites polyactis, Cirrhitichthys oxycephalus and Cirrhi- 
tops fasciatus) the connection also has a linkage with the 
aponeurosis of adductor mandibulae Aw. Here it is effected, 
somewhat indirectly, by a branch from the major mandibulo- 
hyoid connection joining the maxillary tendon of adductor 
mandibulae A, muscle, which tendon itself is derived from 
the aponeurosis of the Aw portion of that muscle. This 
association with the Aw aponeurosis in both cirrhitid groups 
raises the possibility that ontogenetically, the mandibulohy- 
oid linkage is through a tendon and not a ligament as it 
appears to be in the salmonid Oncorhynchus mykiss (see 
Verraes, 1977). It also raises the question whether or not the 
so-called mandibulohyoid ligament (see below) in other 
teleosts (and in the semionotiform Lepisosteidae; see below) 
is truly a ligament. A similar problem arises with the third 
type of mandibulohyoid connection found in cirrhitoids, 
namely that in the latrid Acantholatris monodactylus. Here 
the linkage is not associated with the Aw muscle, and has 
both its origin and its insertion entirely on bone, thus 
appearing to be a true ligament. 

There is some indirect support for the idea that in members 
of the Cirrhitidae the mandibulohyoid connection could be 
derived ontogenetically from the adductor mandibulae 
muscle bloc (sensu Edgeworth, 1935) of the early embryo. 
This stems from the considerable posterior extension of the 
adductor mandibulae Aw aponeurosis onto the bones of both 
the palatoquadrate arch and the interoperculum in certain 
other perciform fishes (see also discussions in Winterbottom, 
1974; Elshoud-Oldenhave & Osse, 1976; Anker, 1978;Green- 
wood, 1985) and, indeed in other cirrhitoids such as the 
cheilodactylids. 

An origin of the mandibulohyoid connection from the 



adductor mandibulae Aw tendon system seems less likely in 
the latrid Acantholatris monodactylus. Here the linkage 
extends from the posterior tip of the dentary's lower arm 
(not, as in the cirrhitids, from its coronoid process or the 
anguloarticular) to the upper part of the ceratohyal's lateral 
face (Fig. 3). At no point has this apparent ligament in 
Acantholatris any association with the adductor Aw muscle or 
any part of its tendon system. With regard to its attachment 
to the lower aspect of the dentary, the connection is compa- 
rable both with the loosely compacted and fibrous linkage 
between the dentary and ceratohyal identified by Aerts et al. 
(1987) in the cichlid Astatotilapia elegans, and with Osse's 
(1969) ligament XXIV in the percid Perca fluviatilis . In both 
these species, however, the tissue has insertions on certain 
branchiostegal rays as well as on the ceratohyal, and in 
neither species does it have the ligament-like appearance of 
the connection in Acantholatris monodactylus. 

Aerts et al. (1987:97) describe in some detail the histology 
of the hyoid-dentary connection in Astatotilapia elegans, 
which seemingly is derived from the anterior, tendinous part 
of the geniohyoideus muscle, with whose dorsolateral aspect 
it is closely associated over much of its length. These authors 
conclude (op. cit.: 99) that 'In fact, the rostral part of the 
interconnection can be interpreted as a parallel elastic com- 
ponent of the protractor hyoidei' (=geniohyoideus). The 
posterior attachment of the connection is on the epi- and 
ceratohyals dorsally, with, as noted above, a number of small 
strands merging into the dermal layers of the skin-fold 
between the hyoid and interoperculum. A mandibulohyoid 
connection, superficially like that in A. elegans also occurs 
(pers.obs.) in another haplochromine cichlid, Thoracochro- 
mis buy si (Penrith); although its histology was not studied, 
the linkage appears to originate from within the geniohyoid 
muscle, and to attach to the hyoid arch at the epi-ceratohyal 
suture. 

At least with regard to its superficial features, Aerts et a/.'s 
description of the dentary-hyoid connection in Astatotilapia 
elegans does not resemble the condition seen in Acantholatris 
monodactylus. Here, the interconnecting tissue is clearly 
separated from the geniohyoideus muscle over virtually its 
entire length, and is much more compact and ligament-like. 
However, posteriorly it does appear to fuse with the tendi- 
nous insertion of the geniohyoideus at the point where both 
elements attach to an elevation on the anterior margin of the 
certohyal. The insertion of the geniohyoideus muscle then 
extends down along the lateral face of the ceratohyal, but that 
of the mandibulohyoid connection does not. Thus in adult 
Acantholatris monodactylus the only suggestion of the con- 
nection being derived from the geniohyoideus muscle is a 
partially shared insertion with that muscle on the ceratohyal. 
That suggestion is, unquestionably, far less convincing than 
the evidence provided by the situation in Astatotilapia 
elegans, but is one that could be clarified if studied ontoge- 
netically in Acantholatris monodactylus. 

A distinct mandibulohyoid ligament, superficially like that 
in Acantholatris monodactylus, has been described by Wiley 
(1976) in the semionotiform gars Lepisosteus and Atrac- 
tosteus. The connection is labeled as a tendon in figure 9 of 
Wiley's paper, but is referred to, I believe correctly, as a 
ligament in the accompanying text. The ligament in gars 
differs from the ligament-like mandibulohyoid connection in 
Acantholatris monodactylus in its points of attachment (epi- 
hyal and retroarticular in the gars, ceratohyal and dentary in 
A. monodactylus). Again, without ontogenetic information 



100 



PH. GREENWOOD 



from both taxa, nothing can be said about its possible 
homology in the two species. 

The concept that a mandibulohyoid connection (usually 
referred to as a ligament) is essentially a feature of pre- and 
lower teleost actinopterygians, has influenced theories relat- 
ing to the evolution of feeding machanisms in teleosts. For 
example, Lauder (1982: 279, also fig. 1) postulated that 'The 
first specialization involves a shift of insertion of the man- 
dibulohyoid ligament to the interoperculum. The interoper- 
culohyoid ligament characterizes the feeding mechanism of 
eurypterygian fishes (=Aulopiformes + Myctophiformes + 
Paracanthopterygii + Acanthopterygii; Rosen, 1973) and 
effectively shifts the action of the hyoid and opercular cou- 
pling onto the interoperculum. Only the interoperculoman- 
dibular ligament transmits posterodorsal hyoid and opercular 
movements to the mandible in the Eurypterygii, while other 
teleosts retain the primitive two-coupling system of the 
halecostomes' (ie both a mandibulohyoid and an 
interopercular-mandibular linkage). Verraes' (1977) studies 
on the development of Oncorhynchus mykiss show unequivo- 
cally that in this teleost there is no ontogenetic shift of the 
mandibulohyoid ligament's mandibular insertion onto the 
interoperculum. Indeed, the interopercular-mandibular liga- 
ment develops independently (and later than the mandibulo- 
hyoid ligament) with both connections persisting in adults 
(Verraes, 1977; pers. obs.); neither is there any ontogenetic 
evidence to show that the epi- (or inter-) hyal to interopercu- 
lum ligament is the result of a preexisting mandibulohyoid 
ligament shifting its mandibular insertion onto the interoper- 
culum. Interestingly in that context, the latrid Acantholatris , 
which has what appears to be a genuine mandibulohyoid 
ligament (see p. 97) also has an epihyal-interopercular liga- 
ment. 

Thus, pace Lauder (1982), it would seem that cirrhitoids 
(and other teleosts) with both a mandibulohyoid connection 
and an interopercular-mandibular ligament have either 
retained the primitive halecostome condition or, as seems 
more likely, re-evolved it through some other form of con- 
nective tissue linkage between the hyoid arch and the man- 
dible. 

Parenthetically, it may be noted that the importance of an 
interopercular-mandibular linkage in the jaw-opening mecha- 
nism of teleosts, stressed by Lauder op.cit. and other authors 
(see for example Liem, 1978 & 1991; Aerts et al., 1987, and 
references therein) is underlined, albeit indirectly, by the 
condition in three of the cirrhitoid taxa examined. In Cheilo- 
dactylus (Cheilodactylidae) and in Mendosoma and Acantho- 
latris (Latridae) there is, in addition to the interopercular- 
mandibular ligament a second such linkage effected through 
an extension of the Aw muscle's aponeurotic system onto the 
interoperculum (see pp. 94 & 97 and Figs 2-4). 

If, as suggested above, certain teleosts have re-evolved a 
mandibulohyoid connection, it may have arisen in different 
ways. This seems probable even within the cirrhitoids {viz. 
cirrhitid and latrid types; see pp. 93 & 94), and in other 
groups as well. In the ostariophysan Hydrocynus vittatus 
(Characidae) for example, the mandibulohyoid connection 
appears to be an extension of the epihyal-interopercular 
ligament which, after its insertion on the dorsal margin of the 
interoperculum, continues forward to bridge the small gap 
between that bone and the retroarticular (pers. obs.). The 
salmonid Oncorhynchus mykiss, by contrast, has no obvious 
association of the mandibulohyoid connection with the 
epihyal-interopercular ligament. Both are discrete entities 



throughout their lengths despite having insertion points close 
together on the epihyal (pers. obs.). The clupeid Etrumeus, 
unlike the preceding examples, has no readily discernible 
mandibulohyoid connection. However, the geniohyoideus 
muscle has a thickened and tendinous dorsal margin which is 
macroscopically continuous with the muscle from the latter's 
origin near the dentary symphysis to its insertion immediately 
over the epi-ceratohyal suture (pers. obs). Superficially at 
least, the situation in this clupeid shares certain similarities 
with the mandibulohyoid link in the perciform cichlid Astato- 
tilapia elegans (see Aerts et al., 1987, and p. 99 above). In the 
clupeid, however, the differention of the linkage from the 
associated muscle is at a somewhat lower level of develop- 
ment than that in the cichlid. 

Verraes (1977) highlighted the functional importance of 
the mandibulohyoid connection in immediately post-hatching 
stages of the salmonid Oncorhynchus mykiss. This apparently 
ligamentous connection develops earlier than the 
interopercular-mandibular ligament. Thus at this point in the 
fish's life-history it is an essential element in bringing about 
jaw depression, and consequently it plays a major role in the 
creation of the trans-buccal water current involved in respira- 
tion and feeding (see also Lauder & Liem [1989] for a 
discussion of this ligament in the feeding mechanism of 
another salmonid, Salvelinus fontinalis). Recently, Aerts et 
al., (1987), working with the cichlid Astatotilapia elegans, 
postulated that a mandibulohyoid connection is also of crucial 
importance in the feeding mechanism in adults of that spe- 
cies. 

Regretably, no experiental work has been carried out on 
the feeding mechanisms of cirrhitoid fishes, nor is there 
enough critical information on their feeding habits to deter- 
mine what correlations may or may not exist between species 
with or without a mandibulohyoid connection. It would be 
interesting to know in what way the mandibulohyoid connec- 
tion functions in cirrhitids such as Cyprinocirrhites polyactis. 
Judging from preserved specimens it would seems to block 
the sinking of the lower jaw when the hyoid is pulled 
posteriorly by the contracting sternohyoideus muscle - a 
somewhat anomalous situation, but possibly one that may be 
associated with a specialized suction mode of feeding on small 
crustacean zooplankters, apparently the principal food of this 
species in South African waters. 

As yet, the intrabuccal tendon and ligament systems are 
known from too few cirrhitoid taxa to test its usefulness in the 
intragroup taxonomy and phyletic relationships of those 
fishes. However, the tendon system in the Cheilodactylidae 
examined, when compared with that in the latrid Acanthola- 
tris monodactylus (cf. Figs 4 & 3) supports the latter taxon's 
removal (see Greenwood, 1995) from the genus Cheilodacty- 
lus and the family Cheilodactylidae in which it had been 
placed previously. Those differences also provide an addi- 
tional character complex for distinguishing the Latridae from 
the Cheilodactylidae. 



Acknowledgements. My thanks go to Professor Tom Hecht and Dr 
Colin Buxton of Rhodes University's Department of Ichthyology and 
Fisheries Science, as well as to their students, for giving me access to 
that Department's collections of preserved material, and for collect- 
ing other specimens when needed. To Dr Phil Heemstra of this 
Institute, my thanks for information on, and discussions about, 
cirrhitoid fishes. For her patience, forbearance and skill, it is a 
pleasure to thank Huibre Tomlinson who once again has turned my 



MANDIBULOHYOID CONNECTION IN CIRRHITOID FISHES 



101 



untidy manuscript into a legible typescript. Anthea Ribbink, who 
also displayed those attributes when producing the anatomical fig- 
ures, deserves my deepest gratitude for her essential contributions to 
this paper. By no means least of all, I am indebted to Drs Mark 
Westneat and Rick Winterbottom for their very constructive com- 
ments on an earlier draft of the paper. 



REFERENCES 



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1978. The morphology of the head-muscles of a generalized Haplochromis 

species: H. elegans Trewavas 1933 (Pisces, Cichlidae). Netherlands Journal 

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Edgeworth, F.H. 1935. The cranial muscles of the vertebrates, vii + 493 pp. 

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the feeding system in the Rutf-Gymnocephalus cernua (L. 1758) - Teleostei, 

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Copeia, 1986: 705-713. 
Greenwood, P.H. 1985. Notes on the anatomy and phyletic relationships of 

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(Teleostei, Percoidei, Cirrhitoidea), with comments on the group's mono- 

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& Liem, K.F. 1980. The feeding mechanism and cephalic myology of 

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1989. The role of historical factors in the evolution of complex organismal 

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Liem, K.F. 1978. Modulatory multiplicity in the functional repertoire of the 
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Osse, J.W.M. 1969. Functional morphology of the head of the Perch (Perca 
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Bull. nat. Hist. Mus. bond. (Zool.) 61(2): 103-109 



Issued 30 November 1995 



A new species of Crocidura (Insectivora: 
Soricidae) recovered from owl pellets in 
Thailand 

PAULINA D. JENKINS 

Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD 

ANGELA L. SMITH 

University of Cambridge, Cambridge 

Synopsis. A new species of Crocidura (white-toothed shrew) is described from owl pellets from Loei Province, 
Thailand. The craniodental morphology is compared with that of similar sized species of Crocidura recorded from 
Thailand. 



INTRODUCTION 



A recent survey of bat roosts and owl pellets in Thailand by 
one of us (ALS) and Mark F Robinson has increased knowl- 
edge of the small mammal fauna of the area. Contained in the 
owl pellets were skulls of 38 species of small mammals, 
including an unknown species of Crocidura. This undescribed 
species has sufficiently distinctive cranial and dental charac- 
ters to warrant its description on the basis of these features 
alone, although the external characters remain unknown. 



MATERIALS AND METHODS 



Regurgitated pellets were collected from roosting sites of 
barn owls (Tyto alba [Scopoli, 1769]) at several localities in 
Thailand. The pellets were dissected and the contents, usu- 
ally incomplete crania and mandibles, were identified as far 
as possible in the field. Voucher specimens were sent to The 
Natural History Museum for confirmation of identification. 
Included among these specimens was a series of Crocidura 
which was proving difficult to identify and was thought to 
include two species, C attenuata Milne-Edwards, 1872 and C. 
fuliginosa (Blyth, 1855). 

Measurements, in millimetres, were taken using dial cali- 
pers or a micrometer eyepiece and measuring stage on a 
microscope. Cranial and dental nomenclature follows that of 
Meester (1963), Mills (1966), Swindler (1976) and Butler & 
Greenwood (1979). Abbreviations for the dental nomencla- 
ture are given in the text. 



RESULTS 



Crocidura hit liana sp. nov. 

Holotype. BM(NH)1994.90, collector's number 467. Cra- 
nium with damaged braincase, left mandibular ramus, com- 



plete maxillary and mandibular dentition. Extracted from an 
owl pellet from a roost at Wat Tham Maho Lan, Ban Nong 
Hin, 48 km south of Loei, Loei Province, northeastern 
Thailand, 17°06'N 101°53'E, altitude 575m. 

Paratypes. Eighteen specimens of crania with mandibles 
and thirteen specimens of crania only, all from owl pellets at 
the same locality as the holotype. Three specimens of crania 
with mandibles and five specimens of crania only from Wat 
Tham Pha Phu, 7 km north of Loei, Loei Province, 17°34'N 
101°42'E, altitude 542m. 

Diagnosis 

Zygomatic process of maxilla broad and angular, interorbital 
region narrow; coronoid process broad and deep. Upper and 
lower first incisors robust, first upper unicuspid large and 
broad relative to the other unicuspids, talonid of the third 
lower molar (M 3 ) reduced to a single cusp. 

Description 

Overlapping in cranial size with medium to large specimens 
of Crocidura attenuata and smaller specimens of C fuliginosa 
but differing from both species in proportions (see Table 1 
and Figs 1-6). Cranium and mandible robust; cranium angu- 
lar in appearance, especially in dorsal view. The rostrum is 
moderately deep and obliquely sloping anteriorly; the maxil- 
lary region is broad, the zygomatic process of the maxilla is 
broad and angular; the interorbital region is long and narrow, 
its width increasing only slightly from anterior to posterior; 
the zygomatic plate is positioned above the first upper molar 
(M 1 ) and the anterior of the second upper molar (M 2 ), its 
posterior face is semi-circular and deeper than the anterior 
face; the braincase is angular, with pronounced angular 
superior articular facets in dorsal view, a squamosal crest is 
present and lambdoid crests are well developed, meeting at 
an acute angle at the midline. The horizontal ramus of the 
mandible is moderately robust; the coronoid process is broad 
and deep (see Fig. 4); the ascending ramus is long and low; 
the condyle is nearly as broad or broader than deep (ratio of 



©The Natural History Museum, 1995 



104 



P.D. JENKINS AND A.L. SMITH 




Fig. 1 Dorsal view of cranium from left to right of C. attenuata BM(NH) 191 1.9.8.26, C. hilliana BM(NH) 1994. 113 and C. fuliginosa 
BM(NH)1933.4.1.183. 



condyle width to height 91.2-113.3), the postero-internal 
ramal fossa has a broad base and is approximately as broad as 
deep; the mental foramen is positioned below the anterior 
part of the first lower molar (M,). 

The dentition is illustrated in Figs 2-6. The first upper 
incisor (I 1 ) is robust, slightly proodont with well developed 
posterolingual and posterobuccal cingula; the upper unicus- 
pids are overlapping and crowded; the first upper unicuspid 
(Un 1 ) is large and broad in comparison with the other 
unicuspids, its breadth is equal to or greater than the distance 
between the two first unicuspids and this tooth is more than 
two thirds the height of I 1 and P 4 ; the second and third 
unicuspids (Un 2 and Un 3 ) are subequal in size; the upper 
premolar (P 4 ) has a moderately small parastyle and robust 
metacone; the first and second upper molars (M 1 and M 2 ) 
show no significant distinguishing features; the third upper 
molar (M 3 ) is short and slender with a slightly compressed 
lingual basin. The first lower incisor (I : ) is robust, long, deep 
and curved, and the anterolingual ridge extends for circa 
three quarters of the length of the tooth, diverging from the 
ventral border, the posterior border of I x lies below the 
middle of the lower premolar (P 4 ); two thirds of the second 
lower incisor (I 2 ) are in contact with I, and one third of the 
tooth is overlapped by P 4 ; the postentoconid ledge is very 
narrow in the first lower molar (M,) and yet more reduced in 
the second lower molar (M 2 ); the talonid of the third lower 



molar (M 3 ) is reduced to a single cusp. 

Etymology 

This species is named in honour of John Edwards Hill, who 
taught one of the authors (PDJ) the basics of mammalogy and 
who also provided invaluable help in the identification of 
some of the skull fragments of bats found during the survey. 

Comparison with other species 

Five species of Crocidura have been recorded from Thailand 
(Lekagul & McNeely, 1977, Davison, 1984): C. fuliginosa 
(including C. dracula Thomas, 1912 listed as a separate 
species by Lekagul and McNeely), C. attenuata, C. pullata 
vorax Allen, 1923 (listed as C. russula vorax), C. horsfieldii 
indochinensis Robinson & Kloss, 1922 and C. monticola 
Peters, 1870. Crocidura hilliana is separated from most 
specimens of C. fuliginosa dracula by its smaller size (see 
Table 1), while it is considerably larger than C. p. vorax 
(condylobasal length <17.5), C. horsfieldii (condyloincisive 
length <17.9, data taken from Heaney & Timm (1983) for 
specimens from Vietnam) or C. monticola (condylobasal 
length <17.4). 

Crocidura hilliana falls at the middle to upper part of the 
cranial size range of C. attenuata and the lower part of the size 



NEW SPECIES OF CROCIDURA 



105 




lllllllllllllllllllllll Illllllllllllllllll 



Fig. 2 Ventral view of cranium from left to right of C. attenuate! BM(NH) 191 1.9.8.26, C. hilliana BM(NH) 1994. 113 and C. fuliginosa 
BM(NH)1933.4. 1.183. 



range of C. fuliginosa (see Table 1). It is readily distinguished 
from both species by its robust, angular cranium, in which the 
maxillary region is broad, the interorbital region narrow and 
the anterior part of the braincase markedly angular (see Figs 
1-3). In contrast, both C. attenuata and C. fuliginosa have a 
proportionally narrower maxillary region, broader interor- 
bital region increasing noticeably from anterior to posterior 
and a more rounded braincase that is evidently broader than 
the maxillary region. Lambdoid crests are more or less well 
developed in both C. hilliana and C. fuliginosa, but they meet 
at an acute angle at the midline in C. hilliana and a shallower 
angle in C. fuliginosa; lambdoid crests are less developed in 
C. attenuata and meet at a shallow angle. Squamosal crests 
are absent or ill defined in C. attenuata, poorly to moderately 
defined in C. fuliginosa but well-marked in C. hilliana. The 
mandible of C. hilliana is considerably more robust than that 
of either of the other two species (see Fig. 4). The horizontal 
ramus of the mandible of C. attenuata is more slender than 
that of C. hilliana, with a sinuous ventral border; the coro- 
noid process is considerably narrower and shallower; the 
ascending ramus is higher and the condyle is higher than 
broad (ratio of condyle width to height 75.0-93.3). The 
horizontal ramus of the mandible of C. fuliginosa is longer yet 
shallower than that of C. hilliana, with a narrower, less robust 
coronoid process and, as in C. attenuata the condyle is higher 
than broad (ratio of condyle width to height 77.8-93.3). The 



mental foramen lies below the posterior part of P 4 in C. 
attenuata and C. fuliginosa but below the anterior of M, in C. 
hilliana. Dentally the most obvious differences between C. 
hilliana and the other two species is the comparatively large 
anterior dentition (I 1 , Un 1 and I x ) relative to the rest of the 
teeth, in combination with the narrow M 3 and the reduced M 3 
of C. hilliana, differing considerably from the condition in 
either C. attenuata or C. fuliginosa (see Table 1 and Figs 2-6). 
In detail the dentition of C. attenuata differs in the follow- 
ing aspects from that of C. hilliana: I 1 is slender and orth- 
odont, the posterolingual cingulum is narrow, Un 1 is 
moderate in size and the distance between the two first upper 
unicuspids is greater than the breadth of Un 1 , Un 2 is smaller 
than Un 1 and Un 3 , and the unicuspids overlap only slightly so 
that the rostrum is moderately long in appearance; the 
parastyle of P 4 is moderately well developed. M 3 is variable in 
different populations of C. attenuata; it is medium sized in 
Indian and Burmese populations and thus readily distin- 
guished from C. hilliana, and although only narrower on 
average in the Chinese populations of C. attenuata, neverthe- 
less, the lingual basin is less compressed than in C. hilliana. 
The first lower incisor of C. attenuata is moderately slender, 
straighter and more procumbent than that of C. hilliana; the 
anterolingual ridge extends for two thirds the length of the 
tooth and is subparallel to the ventral border of the tooth; the 
posterior border of Ij lies below the posterior part of I 2 ; less 



106 



P.D. JENKINS AND A.L. SMITH 



Table 1 A comparison of species of Crocidura occuring in Thailand and nearby countries. 





C. hilliana 


C. attenuata 




C. fuliginosa 








Thailand 


China 


India 


Thailand 


Vietnam 


China 


Condylobasal length 


21.0-23.5 


19.8-20.7 


19.7-21.6 


22.0, 22.8 


21.3-23.4 


21.6-22.7 


mean 


22.20 


20.20 


20.23 




22.58 


22.20 


SD 


0.68 


0.38 


0.54 




0.51 


0.47 


n 


16 


8 


10 


2 


15 


4 


Upper toothrow length 


8.8-10.2 


8.7-9.4 


8.7-9.8 


10.1-10.8 


9.8-10.8 


9.7-10.7 


mean 


9.45 


9.00 


9.12 


10.42 


10.25 


10.17 


SD 


0.35 


0.23 


0.29 


0.29 


0.27 


0.35 


n 


37 


12 


17 


5 


24 


11 


Maxillary breadth at level of M 2 


6.0-7.2 


5.7-6.4 


5.8-6.5 


6.6-7.0 


6.7-7.3 


6.7-7.2 


mean 


6.57 


6.14 


6.08 


6.72 


6.96 


6.91 


SD 


0.30 


0.21 


0.19 


0.16 


0.15 


0.17 


n 


38 


12 


17 


5 


23 


11 


Interorbital breadth 


3.8-4.6 


4.2-4.8 


4.2-4.7 


4.4-4.7 


4.7-5.3 


4.7-5.2 


mean 


4.27 


4.46 


4.39 


4.55 


4.93 


4.93 


SD 


0.21 


0.19 


0.12 


0.13 


0.13 


0.19 


n 


38 


10 


15 


4 


22 


8 


Braincase breadth 


8.9-10.0 


8.5-9.5 


8.7-9.8 


9.9-10.1 


9.8-10.7 


9.9-10.6 


mean 


9.56 


9.09 


9.08 


10.00 


10.24 


10.14 


SD 


0.36 


0.34 


0.33 


0.12 


0.24 


0.26 


n 


16 


9 


11 


3 


18 


5 


Mandible length excluding I, 


10.7-12.7 


10.0-11.5 


10.1-11.2 


11.8-12.4 


11.7-13.1 


11.5-12.7 


mean 


11.35 


10.71 


10.62 


12.09 


12.36 


12.06 


SD 


0.55 


0.46 


0.42 


0.24 


0.35 


0.41 


n 


21 


13 


17 


8 


26 


11 


Mandible height 


5.2-6.3 


4.4-5.1 


4.5-5.2 


5.2-5.8 


5.4-5.9 


5.2-6.0 


mean 


5.78 


4.81 


4.65 


5.54 


5.61 


5.62 


SD 


0.28 


0.22 


0.21 


0.18 


0.16 


0.25 


n 


21 


13 


17 


9 


26 


9 


Interorbital breadth: maxillary breadth 


60.5-70.5 


68.8-77.7 


68.3-77.6 


65.7-69.7 


67.1-75.4 


68.9-73.2 


mean 


65.00 


72.36 


72.40 


67.43 


70.86 


71.09 


SD 


2.44 


2.98 


2.48 


1.66 


2.26 


1.55 


n 


38 


10 


15 


4 


22 


8 


Length of M 3 : upper toothrow length 


5.2-7.0 


6.4-6.9 


7.1-8.0 


6.8-7.9 


6.6-8.0 


6.9-8.0 


mean 


6.12 


6.67 


7.50 


7.48 


7.28 


7.34 


SD 


0.51 


0.16 


0.28 


0.42 


0.42 


0.35 


n 


34 


12 


17 


5 


24 


10 



than half of I 2 is in contact with l 1 and I 2 is one quarter 
overlapped by P 4 ; a postentoconid ledge is present in Mj and 
M 2 ; the talonid of M 3 is relatively complete and an entoconid, 
entoconid ridge and talonid basin are present. 

Crocidura fuliginosa differs from C. hilliana in having a 
moderately slender, orth-opisthodont I 1 with a smaller 
although well developed posterolingual cingulum; Un 1 is 
moderate in size (c half the height of I 1 and P 4 ); in contrast to 
the condition in C. attenuata, Un 2 is only slightly smaller than 
Un 1 and Un 3 ; the lingual region of P 4 is characteristic in 
shape; the mesostyle of M 2 is divided into two stylar cusps 
(see Ruedi, in press) unlike either of the other species; M 3 is 
medium in size and the lingual basin is not compressed. The 
mandibular dentition is similar to that of C. attenuata. In 
particular it is readily distinguished from C. hilliana by the 
less robust, straighter, more procumbent first lower incisor; 
slightly over half of I 2 is in contact with l 1 ; the talonid of M 3 is 
not reduced and an entoconid, entoconid ridge and talonid 
basin are present. 



DISCUSSION 



It is known from the study of barn owl pellets in the British 



Isles and Africa (Glue, 1967; Andrews 1990) that prey 
skeletal elements are subject to little breakage or digestion, 
contrary to the case for pellets of some other avian predators. 
Certainly there is a degree of damage to all of the crania in 
the current sample, none of which are intact. Crania and 
associated mandibles occur in 48%; a few specimens are 
nearly complete showing only minimal damage to the brain- 
case, although the braincase is broken or absent in most 
specimens. The toothrows are complete in 87% of specimens, 
although the teeth may be loose in their sockets, with tooth 
loss occuring generally at the terminal molar or unicuspid 
loci. There is little evidence of digestive erosion of crania or 
teeth. It has therefore proved possible to take most of the 
standard cranial measurements on sufficient of the recovered 
crania and mandibles to obtain significant data on size 
variation. Similarly, the dentition is well preserved so that 
diagnostic characters are readily observed and allowing the 
samples to be aged. Shrews of the genus Crocidura show very 
rapid dental maturation as nestlings, teeth are fully erupted 
shortly after leaving the nest. The dental ages appearing in 
these samples include fully erupted dentitions with no sign of 
tooth wear, probably representing juvenile or subadult speci- 
mens; dentitions showing slight to moderate wear, represent- 
ing adults; dentitions showing extreme wear, representing old 
adults. 



NEW SPECIES OF CROCIDURA 



107 




lllllllllllllllllllllllllilllllllllllllll 



Fig. 3 Lateral view of cranium from top of C. attenuata BM(NH) 191 1.9. 8.26, C. hilliana BM(NH) 1994. 113 and C. fuliginosa 
BM(NH) 1933.4. 1.183. 



There have been few systematic collections of the small 
mammal fauna in Thailand, which in consequence remains 
comparatively little known; in particular the shrews are 
poorly documented. Crocidura fuliginosa was recorded from 
peninsular Thailand by Bonhote (1903), Kloss (1917) [as C. 
aagaardii], Robinson & Kloss (1923) and Hill (1960) [prob- 
ably referring to the same specimen as Robinson & Kloss 
(1923)], and from Koh Samui off the east coast of peninsular 
Thailand by Robinson & Kloss (1914) [as C. negligens]. The 
inclusion in this taxon of two chromosomally distinct but 
morphologically cryptic species in Malaysia was discovered 
recently by Ruedi et at. (1990). Ruedi (in press) has 
attempted to correlate morphological features with these 
chromosomal forms, in order to assign specific names to 
them, reserving the name C. fuliginosa for those specimens 
with chromosomes 2n = 40, Fundamental Number 56 and 
ascribing the other species, with polymorphic chromosomes 
of 2n = 38^0, to C. malayana Robinson & Kloss, 1911. 
Regrettably, examination of Malaysian specimens in the 
collection of the Natural History Museum fails to confirm the 
supposedly clearcut morphological distinction, with some 
specimens exhibiting a mixture of the characters listed by 
Ruedi, so negating the use of these morphological criteria. 
Crocidura fuliginosa is a widely distributed species, occuring 
from Burma in the west to China in the east and southwards 
to Indonesia, including a number of named forms, whose 



taxonomic status has been the subject of considerable discus- 
sion (Medway, 1965, 1977; Jenkins, 1976, 1982; Heaney & 
Timm, 1983; Corbet & Hill, 1992). The presence of cryptic 
species in Malaysia, emphasises the lack of understanding of 
the status of C. fuliginosa, suggesting that it requires further 
revision and might be more appropriately considered as a 
species complex. There are few records of this species from 
regions other than peninsular Thailand, apart from that of 
Lekagul & McNeely (1977) from Chiengmai, or Chiang Mai, 
northwest Thailand (as C. fuliginosa and C. dracula). Fur- 
thermore, there are no specimens of C. fuliginosa from 
Thailand, other than peninsular Thailand, in the collection of 
The Natural History Museum, while in the collection of the 
American Museum of Natural History there are single speci- 
mens from Nakhon Nayok, Khao Yai National Park and 
Nakhon Ratchasima, central Thailand, plus an unconfirmed 
specimen from Umphang, western Thailand. In the current 
survey, C. fuliginosa was identified from prey remains of the 
carnivorous bat, Megaderma lyra E. Geoffroy, 1810 collected 
at Thung Yai-Huai Kha Khaeng Wildlife Sanctuary, western 
Thailand; however there are only a few fragmentary speci- 
mens, dubiously attributed to this species, among the owl 
pellets from Loei Province. There are similarly few records of 
C. attenuata from Thailand; Lekagul & McNeely (1977) listed 
this species from Nakhon Phanom and Udon in the northeast, 
and Chiang Mai, northwest Thailand. There was no evidence 



108 



P.D. JENKINS AND A.L. SMITH 







Fig. 4 Lateral view of mandible from top of C. attenuata 
BM(NH)1911.9.8.26, C. hilliana BM(NH)1994.90 and C. 
fuliginosa BM(NH)1933.4.1.183. 

of C. attenuata either amongst the owl pellet remains from 
Loei Province or from remains found at M. lyra roosts in 
Thung Yai-Huai Kha Khaeng. It is therefore uncertain if C. 
hilliana is sympatric with either C. fuliginosa or C. attenuata. 

Crocidura hilliana does, however, occur sympatrically with 
a smaller species of Crocidura which proved difficult to 
determine from the fragmentary skulls in the owl pellets. 
Allen & Coolidge (1940) collected C. vorax (currently 
grouped with C. pullata Miller, 1911 from the Himalayas, see 
Hutterer, 1993) from northwestern Thailand, while a speci- 
men from Lat Bua Kao, mainland Thailand, attributed to C. 
fuliginosa by Kloss (1919) is also an example of C. p. vorax. 
Several skulls attributable to this species were found in the 
owl pellets from Loei, while a good series was recovered from 
the M. lyra prey remains from Thung Yai-Huai Kha Khaeng, 
where an additional skull was found in the faeces of a large 
carnivore. The only other species of Crocidura listed by 
Lekagul & McNeely (1977) from mainland Thailand was C. 
horsfieldii indochinensis from Chiang Mai and Khao Yai 
National Park . Most recently, Davison (1984), recorded C. 
monticola from penisular Thailand. Neither of the last two 
species mentioned above were identified from either area, 
although pellets from Loei Province contained another shrew 
Suncus etruscus (Savi, 1822), plus a variety of rodent and bat 
species. 

Since there has been so little systematic collection in 
Thailand, it is impossible to make categoric statements about 
the new species, however it seems likely that it is relatively 
localised in its distribution. Even in areas where collecting 



Fig. 5 Lateral view of left anterior dentition. Left: upper toothrow 
(I 1 to P 4 ); right: lower toothrow (I, to P 4 ). Top: C. attenuata 
BM(NH)1911.9.8.26; middle: C. hilliana BM(NH)1994.119 upper 
toothrow, BM(NH)1994.118 lower toothrow; bottom: C. 
fuliginosa BM(NH)1933.4.1.178. Scale 1 mm. 






Fig. 6 Occlusal view of left upper toothrow from left to right of C. 
attenuata BM(NH)1911.9.8.26, C. hilliana BM(NH)1994.121 and 
C. fuliginosa BM(NH)1933.4.1.178. Scale 1 mm. 



NEW SPECIES OF CROCIDURA 



109 



efforts have been more stringent, shrews are frequently 
difficult to trap, perhaps giving a false impression of their 
rarity as faunal components. The discovery of this new 
species of shrew, apparently present as a sufficiently large 
population to form an important and regular part of the diet 
of the resident owls, is therefore not so surprising as it might 
first appear. Because of the nature of the specimens, even 
less information than usual is known about the ecology of the 
new species, although some implications may be drawn from 
knowledge of the ecology and behaviour of the owls. The 
barn owl roosting sites of both collecting localities are caves 
in limestone outcrops in or near temple grounds, surrounded 
by bamboo and deciduous trees. Individual roost sites at Wat 
Tham Maho Lan are generally within 0.5 km of cultivated 
maize fields, while those at Wat Tham Pha Phu are within 1 
km of rice and cassava fields. The home range of barn owls in 
the British Isles and Africa is generally 1-2.5 km, rarely up to 
3 km (Bunn et al. 1982; Andrews, 1990). Because of this small 
hunting range, it may be inferred that this habitat which 
extends for some distance around the roosting site is also the 
habitat for the shrews on which they prey. Barn owls are 
nocturnal and crepuscular in their hunting behaviour, the 
implication being that the shrews are active for at least a 
proportion of the same activity period. 



Acknowledgements. We would like to thank the monks and nuns at 
Wat Tham Pha Phu and Wat Tham Maho Lan for their generous 
hospitality and their help in locating owl roosts. Mr Jarujin Nabhitab- 
hata, Mr Preecha Leucha, Mr Surachit Wargsothorn and Ms Sunee 
of the Ecological Research Department, Thailand Institute of Scien- 
tific and Technological Research, Bangkok, provided much help and 
advice, and kindly allowed access to their reference collection of 
mammal specimens. We are very grateful also to the staff at Wildlife 
Fund Thailand, in particular Mr Surapon Duangkhae, Mr Siripong 
Thonongto and Mr Patric Corrigan, for their help and support. We 
thank Dr Robert Mather (WWF) and his wife Noi, who provided 
logistical support and Dr Mark Robinson who collaborated on the 
survey, for his help and encouragement throughout the project. We 
are indebted to Dr Robert Prys-Jones, Bird Group, The Natural 
History Museum and Dr Rainer Hutterer, Zoologisches Fors- 
chungsinstitut und Museum Alexander Koenig, Bonn, Germany for 
their constructive reviews of the manuscript. 



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Bull. not. Hist. Mus. Lond. (Zool.) 61(2): 111-119 



Issued 30 November 1995 



Redescription of Sudanonautes flowed (De 
Man, 1901) (Brachyura: Potamoidea: 
Potamonautidae) from Nigeria and Central 
Africa 

NEIL CUMBERLIDGE 

Department of Biology, Northern Michigan University, Marquette, Michigan 49855, USA 

CONTENTS 



Introduction Ill 

Systematic Account 112 

Sudanonautes floweri (De Man ,1901) 112 

Distribution 112 

Material 112 

Description 113 

Ecological Notes 117 

Taxonomic Remarks 117 

Acknowledgements 118 

References 118 



Synopsis. The African fresh-water crab Sudanonautes floweri (De Man, 1901) is redescribed from the male syntype 
from Sudan (designated here the lectotype) and a large series of other specimens. The species is recognised by a 
combination of characters of the carapace, chelipeds, mandibles, and gonopods. Sudanonautes floweri is compared 
to related species occurring in Nigeria and Central Africa. The species is found in guinea and woodland savanna 
from northern Nigeria to southern Sudan, in tropical rain forest from south-east Nigeria to northern Angola 
(including Bioko), and along the Zaire river and its tributaries. Sudanonautes floweri is one of the second 
intermediate hosts of the human lung fluke (Paragonimus) in Africa. 



INTRODUCTION 



Recent major works on the taxonomy of the fresh-water 
crabs of Africa (Bott, 1955, 1959, 1964; Monod, 1977, 1980) 
recognise three species of Sudanonautes Bott, 1955 - 5. 
aubryi (H. Milne Edwards, 1853), S. africanus (A. Milne 
Edwards, 1869), and 5. pelii (Herklots, 1861). Since that time 
a number of other species in this genus have been added 
(Cumberlidge, 1991, 1993a, b). The subject of the present 
work, S. floweri (De Man, 1901), was formerly considered by 
both Bott (1955) and Monod (1977, 1980) to be a subspecies 
of 5. aubryi. Sudanonautes floweri is judged here to be a good 
species, and is redescribed from a male syntype from Sudan. 
Gonopod 1 of 5. floweri is distinct (Fig. 2 d-f), and when 
considered in conjunction with other characters of the cara- 
pace and sternum (Fig. 1 a-c) and mandibles (Fig. 2 a-c), can 
be used to identify the species unequivocally. This is impor- 
tant, since S. floweri is one of the four species of Sudanon- 
autes that serve as the second intermediate host of the human 
lung fluke (Paragonimus) in Nigeria and Central Africa 
(Voelker, et al., 1975; Voelker & Sachs, 1977; Nozais, et al., 
1980). However, the ambiguous descriptions of S. floweri and 



S. aubryi in the literature (A. Milne Edwards, 1853; De Man, 
1901; Bott, 1955; Monod, 1977, 1980) have led to the 
misidentification of specimens of S. floweri as S. aubryi by 
parasitologists (Voelker, et al., 1975, fig. 6; Voelker & Sachs, 
1977, fig. 4). 

The right mandible and the right first and second gonopods 
of the type of 5 floweri were removed to illustrate these 
structures from different angles and under magnification (Fig. 
2 a-i). Specimens of S. floweri from Nigeria collected by the 
author were either dug from their burrows at the sides of 
streams, or were trapped in fishing nets set overnight in 
ponds. One specimen (NMU 9. IV. 1983) was caught by hand 
under rocks in a dried river bed, immediately following the 
temporary damming of the river by villagers. Four measure- 
ments, carapace length, carapace width, carapace height, and 
front width, were recorded from each specimen using digital 
callipers. Carapace proportions were calculated according to 
carapace length. These data were pooled and used for 
descriptions of growth (Fig. 3 a,b). Statistical comparisons 
between species were made between sexually mature adults 
only (Table 1). The distribution of S. floweri described here is 
based on the direct examination of a large number of 
specimens from 73 different localities in 9 countries. Litera- 



)The Natural History Museum, 1995 



112 



N. CUMBERLIDGE 



ture records are generally not reliable, and have not been 
included. 

The following abbreviations are used: AMNH, American 
Museum of Natural History, New York, NY, USA; FMC, 
Field Museum, Chicago, IL, USA; MCZ, Museum of Com- 
parative Zoology, Harvard, MA, USA; MNHN, Museum 
National dHistoire Naturelle, Paris; NHM, The Natural 
History Museum, London, UK; NNH, Nationaal Natuurhis- 
torisches Museum, Leiden, The Netherlands; NMU, North- 
ern Michigan University, Marquette, MI, USA; RCM, Royal 
Congo Museum, Tervuren, Belgium; SMF, Senckenberg 
Museum, Frankfurt am M., Germany; USNM, The United 
States National Museum of National History, Smithsonian 
Institution, Washington, DC, USA; ZIM, Zoological Insti- 
tute and Museum, Hamburg, Germany; ZMB, Museum fur 
Naturkunde der Humboldt-Universitat, Berlin, Germany; 
CW = carapace width at widest point; CL = carapace length, 
measured along median line; CH = cephalothorax height, 
maximum height of cephalothorax; FW = front width, width 
of front measured along anterior margin; m = male; f = 
female; coll. = collected by. 



SYSTEMATIC ACCOUNT 



Sudanonautes floweri (De Man, 1901) 

(Figs 1 a-i, 2 a-j, 3 a,b, Table 1) 

Potamon (Potamonautes) floweri; De Man, 1901:94-98, 
100-101, pi. X (fig. 1-7); Rathbun, 1904, pi. XVII (figs 2, 
6); Rathbun, 1905:193-195; Rathbun, 1921:406-410, fig. 6, 
pi. XX (fig. 2); Parisi, 1925:99. 

Potamon (Potamonautes) aubryi; Balss, 1914, p. 405 (except 
ZIM K13557 from Mukonje farm, Cameroon, not Pota- 
mon aubryi H. Milne Edwards, 1853). 

Potamonautes floweri; Balss, 1936:171, fig. 6. 

Potamon floweri; Flower, 1931:734; Chace, 1942:211; 
Capart, 1954:834, fig. 21. 

Sudanonautes (Convexonautes) aubryi floweri; Bott, 
1955:304-306, fig. 65, 100, a-b, pi. XXVIII (fig 2 a-d); 
Monod, 1977:1218; Monod, 1980:384-385. 

Diagnosis. Mandibular palp 2-segmented; terminal seg- 
ment single, undivided, with small hard, hair-fringed flap at 
junction between segments (Fig. 2 a-c). Terminal segment of 
gonopod 1 with raised lobe on cephalic part, separated from 
caudal part by a conspicuous longitudinal groove; subtermi- 
nal segment of gonopod 1 distinctly broadened on outer 
margin (Fig. 2 d-f). Conspicuous raised ridges on sternum at 
points where chelipeds articulate (Fig. 1 c). Carapace greatly 
arched (CH/CL = 0.61, Fig. 1 b), very wide (CW/CL = 1.51, 
Fig. 1 a). Vertical suture separating sub-branchial and subor- 
bital regions meeting anterolateral margin at base of interme- 
diate tooth (Fig. 1 b). 

Distribution. Nigeria, Cameroon, Bioko (= Fernando 
Po), Central African Republic, Sudan, Zaire, Congo, Gabon, 
Cabinda, Angola. It is likely that S. floweri is also present in 
Equatorial Guinea. Rathbun (1921) and Balss (1936) pro- 
vided details of the distribution of the species in Zaire. 
Monod (1980) reported S. floweri from the basins of the Nile, 
Zaire, Chari, and Lake Chad. The present work adds several 
new localities in Nigeria, Bioko, and northern Angola. 



MATERIAL 



Lectotype. NHM reg. 1901.8.26.2, lm (CW 48.5, CL 30.5, 
CH 17.8, FW 11.7 mm), from Bahr el Gebel, Sudan, coll. 
Capt. S. S. Flower, 26.viii.1901. This specimen is here 
designated the lectotype of S. floweri. De Man did not specify 
types, so the material he examined was syntypic. 

Others. The catalogue number of material held at NHM 
and NMU begins with the date (year, month, day) of 
collection or acquisition. NIGERIA. NHM 1895.5.5.1^1, 
Asaba, 150 miles up the Niger, coll. N. H. Crosse. NHM 
1905.6.5.98-100, Sapele, junction of Jameson and Aethiop 
rivers, coll. Dr. Ansoroye. NHM 1910.4.30.19-22, Oban 
southern Nigeria, coll. P. A. Talbot. NHM 1938.7.1, Obubra, 
southern Nigeria, coll. I. Sanderson. RCM 52.889, Jos, 1967, 
coll. E. B. Guong. NMU 8-12.V.1975, Rosse, at Iguoriokhi, 
Bendel State, If, 8-12. v. 1975, coll. Bruce Powell. NMU 
24. IV. 1980, first or second roadside culvert, Calabar, If (CW 
45.5 mm) dug from burrow, coll. J. C. Reid. NMU 
30. IV. 1982, Ogoja, Cross River State, lm, CW 50 mm, dug 
from hole at edge of swamp at Ogoja, rain forest/ woodland 
savanna, coll. B. D. Barrett. NMU 4.1.1983, Kaduna river 
(year-round flow), Kaduna State, 4m, coll. Fatima Abdulka- 
dir. NMU 1. III. 1983, dug from holes, Kaduna, Kaduna 
State, coll. Fatima Abdulkadir. NMU 4.IV.1983, foot of 
Obudu plateau, Cross River State, lm, fast white water, big 
rocks, small rocks, sand gravel bottom, caught by villagers, 
who dammed stream, dried river bed, caught crabs under 
rocks, (with S. africanus, S. granulatus), coll. N. Cumber- 
lidge. NMU 12. XII. 1983, Yankari Game Reserve, Bauchi 
State, Hippo Pool, dug from holes, lm, If, coll. N. Cumber- 
lidge. NMU 30. IV. 1984, pond near tributary of river Niger 
(20 km east of river), Otta, Benue State, If, (CW 54 mm), 
coll. John Iyage. NMU 12. VI. 1984, dug from holes in banks 
of river Samu, tributary of Niger, Pasakwauri, near Kagoro, 
Kaduna State, lm, If, coll. N. Cumberlidge. ZIM K3484, 
Benin, lm, 2f, xii.1909, coll. C. Manger. ZIM K30252, Njaba 
creek, 15. hi. 1973, coll. J. Voelker. ZIM K30314, Cross river, 
near Arochukwu, 6.iv.l974, coll. J. Voelker. CAMEROON. 
NHM 1938.7.1.9-13, Mamfe, coll. I. Sanderson. NHM 
2. VIII. 1968, Kindongo, south Bakundu, west Cameroon, in 
hole on forest floor about 100 yds from nearest (non- 
permanent) water, coll. T. S. Jones. RCM 54.190, Kombe- 
tiko, 5 km from Batouri, river Tanadi, 3 specimens, 2.ii.l976, 
coll. F. Puylaert. RCM 53.389, Olounou, 15-30 specimens, 
15-17.viii.1971, coll. F. Puylaert. RCM 54.198, Bissiri May- 
erey, 20. i. 1976, coll. F. Puylaert. SMF 2098, Bibundi, 
20.viii.1948, coll. Justus Weil. SMF 2868, Bibundi, coll. 
Justus Weil. SMF 1787, Victoria, 1907, O. Valley. NMU 
24.X. 1970, near Mamfe, crossing road by Baduma village, 
Kumba-Mamfe road, If, coll. R. H. L. Disney. ZIM K3526, 
lm, If, 24.xii.1911, coll. Dr. E. Fickendey. ZIM K25447, 
Duala, lm, 4.X.1912, C. Manger. ZIM K30397, Kembong, 
near Mamfe, 26. iv. 1975, coll. J. Voelker. ZMB 5552, Djeer- 
fluss, lm, coll. Schweinfurth. ZMB 7789, Benue, 
4-9. viii. 1889, coll. Staudinger. ZMB 8234, Barombi Lake, If, 
coll. Zeuner. ZMB 10023, If, coll. Preuss. ZMB 10216, 
Johann Albrechtshohe (modern name unknown, 4°40'N, 
9°20'E), If, coll. Conradt. ZMB 13718, Victoria, If, coll. 
Deutsche Tiefsee Expedition. ZMB 14342, Douala, 2f, 
5.xi.l910, coll. Shaeffer. ZMB 16440, Barombi Station, lm, 
1891, coll. Preuss. ZMB 16947, Douala, lm, coll. Thorbeke. 



REDESCRIPTION OF AFRICAN FRESH- WATER CRAB 



113 



ZMB 20161, Buea, 6f, 16. xi. 1892, coll. Preuss. ZMB 20195, 
Buea, lm, If, coll. Preuss. ZMB 20199, Victoria, 4m, coll. 
Preuss. ZMB 21300, river Sanaga, Douala grassland district, 
1200 m, lm, ll.i.1917, coll. Elbert. ZMB 21308, Douala, If, 
coll. Thorbeke. CENTRAL AFRICAN REPUBLIC. RCM 
55.399, Giako river, Bougua, 26. ii. 1982, coll. L. de Vos & J. 
Kempeneeus. RCM 53.086, near Bangui, 22.xii.1967. 
SUDAN. NHM 1912.12.31.52, Nyonki Nile, 2030 feet, If, 
hatchlings, 28. iv. 1912, coll. Sir F. T. Jackson. NHM 
1912.12.31.53, Gondokoro, 1800 feet, 12.iv.1912, coll. Sir F. 
T. Jackson. NHM 1913.9.10.1-3, Lado Nipo, 15 miles north 
of Kojokaji, coll. S. S. Flower, zoological survey of Egypt. 
NHM 1913.9.10.9-10, new cut to Zeraf, north of Shamfe, 
coll. G. W. Graham. NHM 1918.12.13.1-3, Mongalla, coll. 
S. S. Flower, Zoological Survey of Egypt. NHM 
1922.11.22.7-11, Mongalla, Kanisa, vi.1914, coll. S. S. 
Flower, Zoological Survey of Egypt. FMC, 400 miles west of 
Juba, 7m, 18f, 22.xii.1884. ZAIRE. RCM 1666, Buta, 1934, 
coll. F. Hutsebout. RCM 1.661-1.665, Bambesa, l.viii.1924, 
coll. J. Brejko. RCM 47.495, Epulu, ix.1956, coll. Dr. M. 
Poll. RCM 46.159-46.160, Ngense, 1955. RCM 
46. 161-46. 162, Ngense, 1955. MNHN BP5049, river Dougou, 
affluent of Uele, lm, coll. L. Didier, Mission du Bourg 
Bozas, 1903. MCZ 10612, Faradje, lm If, 21-23. ix. 1915. 
SMF 2405, Luki, coll. E. Dartevelle. SMF 2398, Ganda 
Sundi, coll. E. Dartevelle. SMF 2385, Faradje, upper Uele, 
v. 1925, coll. Dr. Schoudeten (exchange, RCM 1083, 1079). 
SMF 2383, Bambesa, coll. Krydag. SMF 1782, Duma, coll. 
Telinbotz. All of the following AMNH material coll. H. 
Lang, J. Chapin, AMNH Congo Expedition. AMNH 3338, 
Faradje, 5m, 2f. AMNH 3339, Faradje. AMNH 3355, 
Faradje, 3m. AMNH 3357, Faradje, 3m, If, x.1912. AMNH 
: 3358, affluents of Nepoko river, near Gamangui (Ituri For- 
est), 3m, If. AMNH 3359, Banana, 3m. AMNH 3359, Poko, 
lm, 4f, x— xii.1913. AMNH 3377, affluents of Nepoko river, 
i near Gamangui (Ituri Forest), 3m, If. AMNH 3406, south of 
< Poko, x-xii.1913. AMNH 3409, affluents of Nepoko river, 
! near Gamangui (Ituri Forest), lm. AMNH 3422, Van Kerck- 
hoverville, 2m, If, iv.1912. AMNH 3448, Faradje, If, 1911. 
| AMNH 3453, Poko, lm, 4f, viii.1909. AMNH 3458, north of 
Ganza, If (ovig), 16.xii.1909. AMNH 3462, affluents of the 
Tshope river, near Stanleyville. AMNH 3465, Yakukuku, 
lm; Garamba, If, xi.1911. BIOKO. NHM 1905.7.19.12, coll. 
Fernando Po Exploration Committee. ZMB 20164, lm, If, 
vii.1900, coll. Conradt. GABON. NHM 1908.6.2.22, Lam- 
barene, Ogoue river, coll. M. Ansorge. NHM 
1908.6.2.23-24, Abanga river, Ogoue river. NHM 
1908.6.2.25, Fang forest, Ogoue river, caught on a mountain- 
top during heavy tropical rain, 29. iv. 1907. NHM 
1908.6.2.25a, Masoma river, Ogoue river. AMNH 3367, 
Libreville, 5m, 5f, ii.1916, coll. H. Lang, J. Chapin. AMNH 
3369, 3m, 2f, 1916, coll. H. Lang, J. Chapin. FMC, Gabon or 
Middle Congo, French Equatorial Africa, 1951-1952, coll. H. 
A. Beatty. CABINDA. MNHN BP5048 (lm, CW 54.7, CL 
'36.0 mm), BP5047 (If, CW 56.6, CL 39.5 mm) Landana, 
Cote de Loango, 4.ix.l898, coll. M. Petit. ANGOLA. NHM 
1912.4.2.1-3, Luali river. 



DESCRIPTION OF MALE LECTOTYPE 



Carapace (Fig. 1 a,b). Ovoid, extremely wide, widest in 



anterior third (CW/CL = 1.51), extremely high, with maxi- 
mum height in anterior region (CH/CL = 0.61). Anterior 
margin of front straight, curving under, front relatively 
narrow, about one-quarter carapace width (FW/CW = 0.25). 
Surface of carapace smooth with no deep grooves. Postfron- 
tal crest consisting of fused epigastric, postorbital crests, 
lateral ends with slight crenulations; mid-groove broad, shal- 
low. Postfrontal crest contrasting colour to carapace, located 
very close to, almost touching, postorbital margin; laterally, 
postfrontal crest meeting, or nearly meeting, anterolateral 
margin of carapace at, or near, epibranchial tooth. Exo- 
orbital tooth blunt, low, intermediate tooth smaller than 
exo-orbital tooth, epibranchial tooth small, low, a granule. 
Anterolateral margin of carapace raised and granulated, 
bigger granules at epibranchial corner, smaller granules 
behind, continuous with posterolateral margin, or curving 
slightly inward in hepatic region. Posterior margin about 
two-thirds as wide as carapace width. 

Face of of carapace with 2 sutures, 1 longitudinal, 1 
vertical, dividing face and sides into 3 parts (Fig. 1 b). 
Longitudinal suture dividing suborbital, subhepatic regions 
from pterygostomial region, beginning under inferior medial 
margin of orbit, and curving backward across side. Short, 
curving, vertical suture dividing suborbital region from sub- 
hepatic region (Fig. 1 b); suture beginning beneath interme- 
diate tooth, curving down to meet longitudinal suture, 
marked by row of small rounded granules. Third maxillipeds 
(Fig. 1 d) filling entire oral field, except for transversely oval 
efferent respiratory openings at superior lateral corners; long 
flagellum on exopod of third maxilliped; ishium of third 
maxilliped smooth, with faint vertical groove; merus with 
flanged edges. Mandibular palp 2-segmented, terminal seg- 
ment single, undivided, small hard, hair-fringed flap at junc- 
tion between segments (Fig. 2 a-c). 

Pereiopods (Fig. 1 f-i). Chelipeds of lectotype unequal, 
right longer, higher than left. Dactylus of right cheliped not 
arched, fingers enclosing long interspace when closed, palm 
of propodus swollen. Fingers of right cheliped with 4 larger 
teeth on lower digit and 4 larger teeth on upper digit, 
interspersed with a series of smaller pointed teeth along their 
lengths. Inferior margins of merus with rows of small teeth, 
cluster of granules surrounding larger tooth at distal end. 
Carpus of cheliped with 2 large pointed teeth on inner 
margin, second smaller than first. Left cheliped similar to 
right, but smaller in all respects. Walking legs (pereiopods 
2-5) slender (Fig. 2 j), third pair longest, fourth pair shortest. 
Posterior margin of propodus of walking legs serrated, dactyli 
of walking legs tapering to point, each bearing rows of 
downward-pointing sharp bristles; dactylus of fourth pair 
shortest (Fig. 2 j). 

Underside. First transverse groove on sternum (between 
sternal segments 2 and 3) complete; second groove (between 
sternal segments 3 and 4) consisting of 2 small notches at sides 
of sternum; sternum with conspicuous raised ridges at points 
where chelipeds insert (Fig. 1 c). Segments 1-6 of abdomen 
four sided, last segment triangular, sides indented, rounded 
at distal margin (Fig. 1 e); segment 3 broadest, segments 3-7 
tapering inwards (Fig. 1 e). 

Terminal segment of gonopod 1 long (2/3 as long as subtermi- 
nal segment), first half straight continuation of subterminal 
segment, second half curving outward, tapering to pointed tip; 
terminal segment with raised lobe on the cephalic part, separated 



114 



N. CUMBERLIDGE 




Fig. 1 Sudanonautes floweri, lectotype, adult male from Bahr el Gebel, Sudan (CW 48 mm), NHM reg 1901.8.26.2. (a), whole animal, 
dorsal aspect; (b), carapace, frontal aspect, (c) sternum; (d) left third maxilliped; (e), abdomen; (f), right cheliped, frontal view; (g), left 
cheliped, frontal view; (h) carpus, and merus of right cheliped, superior view; (i) carpus, and merus of right cheliped, inferior view. Scale 
bar equals 15 mm (h, i), 10 mm (c, f, g), 7.5 mm (a, b, e), and 3.75 mm (d). 



from the caudal part by a distinct longitudinal groove visible from 
caudal and superior views (Fig. 2 d,f), not visible from cephalic 
view (Fig. 2 e). Subterminal segment of gonopod 1 broadened 
conspicuously on outer margin, fringed with bristles (Fig. 2 d,e), 
with raised flap extending halfway across segment in distal part, 



tapering diagonally to point at junction with terminal segment, 
forming roof of chamber for gonopod 2; subterminal segment 
beneath flap forming lower floor of chamber for gonopod 2 (Fig. 
2 d). Gonopod 2 (Fig. 2 g-i) shorter than gonopod 1 (reaching 
only to the junction between last 2 segments of gonopod 1). 






REDESCRIPTION OF AFRICAN FRESH- WATER CRAB 



115 




Fig. 2 Sudanonautes flowed, lectotype, adult male from Bahr el Gebel, Sudan (CW 48 mm), NHM reg 1901.8.26.2. (a), right mandible 
anterior view; (b), right mandible superior view; (c), right mandible posterior view; (d), left gonopod 1, caudal view; (e), right gonopod 1, 
caudal view; (f), right gonopod 1, superior view; (g), right gonopod 2, cephalic view; (h), right gonopod 2, caudal view; (i), right gonopod 
2, caudal view, detail of terminal segment; (j) left pereiopod 2. Scale bar equals 10 mm (j), 1.5 mm (a-c, d-h), and 0.5 mm (i). 



Terminal segment gonopod 2 cup-shaped, with pointed tip, 
extremely short, only 1/15 as long as sub-terminal segment. 
Subterminal segment gonopod 2 widest at base, then tapering 
sharply inward, forming long, thin, pointed, upright process 
supporting short terminal segment. 



Adult female. Right, left chelipeds same proportions as 
male of same size, unequal in both length, height. Mature 
female abdomen very wide reaching coxae of pereiopods 2-5. 
Segments of female abdomen becoming gradually longer 
distally, first, fifth becoming gradually wider, abdomen being 



116 



N. CUMBERLIDGE 



widest at groove separating fourth, fifth segments. Sixth 
segment, telson together forming near semicircle. 

Growth (Fig. 3 a,b, Table 1). Measurements and propor- 
tions given in Table 1, Fig. 3 a,b. Sexual maturity judged by 
development of female abdomen: abdomen of mature 
females overlapping bases of coxae of walking legs, pleopods 
broad, hair-fringed. Pubertal moult, from pubertal stage to 
sexual maturity, occurring between CW 33—42 mm. Largest 
known specimen, (male from Cameroon) CW 60.4, CL 39.9. 
In Zaire, eggs produced in December; in Sudan, hatchlings 
present in April. Dimensions of carapace varying with age 
(Fig. 3 a). Relative proportions of carapace width (CW/CL) 
and height (CH/CL) of juvenile and pubescent 5. flowed not 
significantly different (P >0.05) from adults (Fig. 3 b). Front 
width becoming smaller with age: FW/CL of adult S. floweri 
significantly more narrow (P <0.001) than that of juvenile 
and pubescent animals (Fig. 3 b). 

Colour. (Living adults from Ogoja, Nigeria). Dorsal cara- 
pace dark purplish brown, with a contrasting yellow-orange 
postfrontal crest and yellow orbital border. Flanks light 
brown, third maxillipeds pale brown with purple tinge, eye- 
stalks white cream, cornea black, sternum and abdomen light 
brown with purple tinge. Arthrodial membranes between 
joints of chelipeds and pereiopods dark brown; dorsal surface 



Table 1 Means (± SE) of ratio of carapace width (CW), carapace 
height (CH), and front width (FW), to body size (CL) of adult 
Sudanonautes floweri compared to the adults of six closely related 
species of Sudanonautes from Nigeria and Central Africa. 



CW/CL 
X±SE 



CH/CL 
X±SE 



FW/CL 
X±SE 



Sudanonautes floweri 
Sudanonautes aubryi 



1.52 ± 0.01 0.61 ± 0.0 10.38 ± 

0.003 
(n = 65) 
1.37 a ± 0.01 0.52 a ± 0.01 0.38 ± 0.002 
(n = 63) 
Sudanonautes africanus 1.38 a ± 0.01 0.43" ± 0.003 0.36 c ± 0.004 

(n = 26) (n = 14) {n = 15) 

Sudanonautes granulatus 1.42 a ± 0.01 0.51 a ± 0.01 0.41 a ± 0.01 

(n = 33) 
Sudanonautes monodi 1.49 a ± 0.01 0.58 b ± 0.004 0.39 ± 0.004 

(n = 23) 
Sudanonautes kagoroensis 1.52 ± 0.02 0.50 a ± 0.01 0.39 ± 0.004 

(n = 9) 

Sudanonautes orthostylis 1.45 a ± 0.02 0.51 a ± 0.01 0.46 a ± 0.01 

(n = 10) 



Proportion significantly different from that of 5. floweri: a = P 
<0.001; b = P <0.01; c = P <0.05. 



m 
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10 15 20 25 30 35 40 45 
Carapace Length (mm) 



10 15 20 25 30 35 40 45 
Carapace Length (mm) 






Fig. 3. Comparisons of 108 specimens of Sudanonautes floweri. a, dimensions of the carapace (CW, CH, FW) compared to body size (CL), r 
values (all at df = 107) indicate a highly significant correlation (P <0.001) between size classes, b, relative proportions of carapace width 
and height (CW/CL, CH/CL) compared to body size (CL), r values (both at df = 107) indicate no significant correlation (P >0.05) between 
size classes; relative proportions of front width (FW/CL) compared to body size (CL), r value (at df = 107) indicates a highly significant 
correlation (P <0.001) between size classes. 



REDESCRIPTION OF AFRICAN FRESH-WATER CRAB 



117 



of chelipeds and pereiopods light brown, ventral surface light 
brown. Specimens from the Ogoue river, in the Fang forest, 
Gabon, with brown-pink carapace, shading into neutral 
orange in middle; walking legs orange-vermillion. 

Variation. The anterolateral margin is raised, marked by a 
series of granules or small teeth in some specimens (from 
Juba, Shambe, and Kojo-Kaji, Sudan; Ituri forest, Banana, 
and Faradje, Zaire; and Ogoja, Kaduna, and Bendel State, 
Nigeria). In other specimens (Poko, Zaire; Fernando Po, and 
Luali, Angola) the anterolateral margin is completely 
smooth. In specimens from Oban, Nigeria, the anterolateral 
margin is smooth except for the epibranchial tooth (which is 
the size of a large granule), followed by two smaller granules. 
It is possible that the above variations of the anterolateral 
margin are due to changes associated with growth. For 
example, the adult male (CW 53.5 mm) from Juba, Sudan 
(FMC) was the only one in which the anterolateral margin 
was smooth out of 25 specimens of all sizes. This margin was 
toothed or serrated in all the other specimens which mea- 
sured CW 48 mm or less. A similar observation was made in 
the series of specimens from Cameroon (RCM 53.389), 
where the anterolateral margin of a large male (CW 60.4 mm) 
was completely smooth, but that of smaller specimens was 
granulated. Some specimens from Juba, Sudan, had serra- 
tions on the dorsal surface of the dactylus of the cheliped 
while other specimens from Juba, and from Nepoko, Zaire, 
lacked these serrations. 



ECOLOGICAL NOTES 

Sudanonautes flowed is a common species of fresh-water crab 
widely distributed in Nigeria and Central Africa. It is found in 
the moister regions of the woodland and guinea savanna 
zones from central Nigeria to southern Sudan. This species is 
also found in the humid tropical rain forest habitats in 
south-east Nigeria, south Cameroon, Bioko, Central African 
Republic, Zaire, Congo, and Gabon. In Nigeria, 5. floweri 
occurs in the drainage basins of the lower Niger, Benue and 
Cross rivers. Specimens collected from Yankari Game 
Reserve, Bauchi State, Nigeria were dug from holes at the 
base of tufts of tall grass clumps in a marsh at the confluence 
of rivers Yashi and Gaji, an area heavily trampled by big 
igame, especially elephants. Many specimens of S. floweri 
('were caught on land during heavy tropical rain. 

In Sudan, 5. floweri lives both in the Yei river basin (a 
tributary of the Nile), in the mountainous watershed between 
the Nile and the Zaire rivers, and in the level papyrus swamps 
(Flower, 1931). In Zaire, 5. floweri has been reported from 
the lower and middle reaches of the Zaire river, and in the 
Ubangi and Uele rivers (Rathbun, 1921). The habitat of 5. 
floweri in Zaire has also been described by Rathbun (1921), 
who summarised the field notes of Herbert Lang. 5. floweri 
iwas often found in heaps of rotting vegetation in water 
icourses, and Lang speculated that this habit may carry the 
crabs downstream, explaining (at least in part) the wide 
jdistribution of this species. Predators of S. floweri in the rain 
jforests of Zaire include crocodiles, monitor lizards (Varanus 
niloticus), insectivorous otter shrews (Potamogale velox) and 
several small carnivores, chiefly species of mongooses and the 
African civet (Viverra civetta). 

Sudanonautes floweri is common in shallow streams, rivers, 



and ponds, and digs burrows near waterways. This species is 
also found on land either next to water or some distance 
away, since it is capable of breathing air, and functions well 
for long periods out of water. The widened and highly arched 
carapace, and the lack of teeth on the anterolateral margins 
of the carapace of S. floweri are features often associated with 
air-breathing and burrow-living. This body shape contrasts 
with the more flattened, deep-grooved, and spiny carapace of 
the more aquatic river-living species such 5. faradjensis 
(Rathbun, 1921). 



TAXONOMIC REMARKS 

The difficulties in distinguishing between 5. aubryi and 5. 
floweri date back to the work of Rathbun (1904, 1905). 
Although Rathbun (1905) described S. floweri and S. aubryi 
as separate species, her description of P. (P.) aubryi was 
based largely on specimens of 5. floweri. Specimens from 
Cabinda (MNHN B5048) and Zaire (BP 5049) used by 
Rathbun (1905) to describe S. aubryi have been examined in 
the present study and found to be S. floweri. This opinion is 
supported by the photographs of the specimens from Zaire 
and Gabon provided by Rathbun (1904: TVI, plate IX, figs 5, 
8) which closely resemble S. floweri, and which are clearly 
different from the photograph of the female type of 5. aubryi 
(Rathbun, 1904: TVI, plate IX, fig. 3). Unfortunately, Rath- 
bun's (1905) ideas were accepted by later workers with the 
result that the descriptions of 5. aubryi in Balss (1914, 1929), 
Capart (1954), Bott (1955) and Monod (1977, 1980) all refer 
to S. floweri rather than to S. aubryi sensu H. Milne Edwards 
(1853). 

Comparisons. Six species of Sudanonautes are sympatric 
with S. floweri in Nigeria and Central Africa, viz. 5. granula- 
ns (Balss, 1929), S. kagoroensis Cumberlidge, 1991, S. 
orthostylis Bott, 1955, S. monodi (Balss, 1929), 5. aubryi, and 
S. africanus. These taxa can be distinguished from 5. floweri 
as follows. The small hard flap on the mandibular palp at the 
junction between the two segments (Fig. 2 a-c), and the 
conspicuous raised ridges on the sternum at the points where 
the chelipeds insert (Fig. 1 c), distinguish S. floweri from all 
other species of Sudanonautes, which lack these features. 

In addition, the raised lobe on the cephalic part of the 
terminal segment of gonopod 1, separated from the caudal 
part by a conspicuous longitudinal groove in S. floweri (Fig. 2 
d,f) is also shared, in varying degrees, by S. monodi, S. 
kagoroensis and S. granulatus. These three species can be 
further distinguished from 5. floweri by the following charac- 
ters. The raised lobe on the cephalic part of the terminal 
segment of gonopod 1 of S. monodi (Cumberlidge, 1991) is 
considerably higher than that of S. floweri. In addition, the 
carapace of S. monodi is significantly (P <0.001) flatter 
(CH/CL 5. monodi = 0.52, S. floweri = 0.61), and less wide 
(CW/CL 5. monodi = 1.37, S. floweri = 1.51) than that of 5. 
floweri (Table 1). Sudanonautes monodi has patches of 
granules on the anterior corners of the carapace behind the 
postfrontal crest, while S. floweri lacks these granules. 
Finally, S. monodi is found in dry sudan savanna from 
Nigeria to Sudan, while S. floweri is absent from this region; 
and S. monodi is absent from woodland savanna and rain 
forest where 5. floweri is abundant. 

Sudanonautes kagoroensis was described by Cumberlidge 



118 



N. CUMBERLIDGE 



(1991), and can be distinguished from S. flowed by examina- 
tion of gonopod 1: the raised lobe on the cephalic part of the 
terminal segment in 5. kagoroensis is lower than that in S. 
floweri, and the outer margin of the subterminal segment of 
gonopod 1 is slim, while that of 5. floweri is conspicuously 
broadened (Fig. 2 d, e). Furthermore, the carapace of S. 
kagoroensis is significantly (P <0.001) flatter (CH/CL = 
0.44) than that of S. floweri (CH/CL = 0.61). 

Sudanonautes granulatus was redescribed by Cumberlidge 
(1993a) and can be distinguished from S. floweri as follows. 
The carapace of S. granulatus is significantly (P <0.001) 
flatter (CH/CL 5. granulatus = 0.51, S. floweri = 0.61), and 
less widened (CW/CL S. granulatus = 1.41, S. floweri = 1.51) 
than that of S. floweri (Table 1). In addition, the dactylus of 
the major cheliped of the adult male of S. granulatus is 
dramatically arched, while that of 5. floweri is only moder- 
ately arched; the major cheliped of adult male S. granulatus is 
as long as, or longer, than the carapace width (Cumberlidge, 
1993a), whereas that of S. floweri is shorter (Fig 1 f) than the 
carapace width (Fig. 1 a,b). 

Three other species, S. aubryi, S. africanus, and S. ortho- 
stylis, differ from S. floweri in that the terminal segments of 
gonopod 1 of these species lack both a raised cephalic lobe, 
and a distinct longitudinal groove in the caudal view. These 
three taxa can be further distinguished from S. floweri as 
follows. The carapace of S. aubryi is significantly (P <0.001) 
flatter (CH/CL S. aubryi = 0.52, S. floweri = 0.61), and less 
wide (CW/CL S. aubryi = 1.37, S. floweri = 1.51) than that 
of S. floweri (Table 1). In addition, the carapace and post- 
frontal crest of S. aubryi are a green-brown colour, whereas 
these parts of S. floweri are uniformly red-brown with a 
contrasting yellow postfrontal crest. 

The terminal segment of gonopod 1 of S. africanus is thin 
and needle-like, while that of S. floweri (Fig. 2 d) is wider and 
has a distinct groove in the caudal view. The carapace of S. 
africanus is significantly (P <0.001) flatter (CH/CL S. africa- 
nus = 0.43, S. floweri = 0.61) and less wide (CW/CL 5. 
africanus = 1.38, S. floweri = 1.51) than that of S. floweri 
(Table 1). The carapace of S. africanus has patches of raised 
warts, while that of S. aubryi is completely smooth. Finally, 
the pollex of the propodus of the major cheliped of 5. 
africanus has a large and conspicuously flattened tooth, which 
is lacking in adult S. floweri. 

Sudanonautes orthostylis was redescribed by Cumberlidge 
(1993b), and can be distinguished from S. floweri as follows. 
The terminal segment of gonopod 1 of 5. orthostylis is 
straight, lacks a visible groove, and curves outwards sharply 
only at the tip, while that of S. floweri bears a longitudinal 
groove and curves from the mid point (Fig. 2 d). The 
carapace of S. orthostylis is significantly (P <0.001) flatter 
(CH/CL 5. orthostylis = 0.51, S. floweri = 0.61), and less 
wide (CW/CL S. orthostylis = 1.44, S. floweri = 1.51) than 
that of S. floweri (Table 1). The frontal margin of S. 
orthostylis is significantly (P <0.001) wider than that of S. 
floweri (FW/CL S. orthostylis = 0.46, S. floweri = 0.38, Table 
1). The dactylus of the major cheliped of S. orthostylis is 
broad and flat, while that of S. floweri is narrow. Finally, 5. 
orthostylis is a much smaller species, maturing at CW 22 mm, 
compared to maturity between CW 33-42 mm in S. floweri. 



Acknowledgements. I am very grateful to Mr. Paul Clark and Ms. 
Miranda Lowe (NHM, London), Drs. D. Guinot and J. Forest 
(MNHN, Paris), and Mr. Trefor Williams (University of Liverpool, 



UK) for loaning the specimens used in this work. The following 
people are thanked for hosting visits: Dr. H. Feinberg, AMNH, New 
York, USA; Ms. Ardis Baker Johnston, MCZ, Harvard, MA, USA; 
Mr. Paul Clark, NHM, London, UK; Drs. L. Holthuis and C. 
Fransen, NNH, Leiden, The Netherlands; Dr. R. Joque, RCM, 
Tervuren, Belgium; Dr. R. Manning, USNM, Washington DC; Drs. 
H.-G. Andres and G. Hartmann, ZIM, Hamburg, Germany; Dr. H. 
Gruner, ZMB, Berlin, Germany; and the staff of the FMC, Chicago, 
USA. I especially thank artist Mr. Jon C. Bedick of Northern 
Michigan University, USA, for all of the illustrations used in this 
paper. Part of this work was supported by a Faculty Grant from 
NMU, Marquette, MI, USA. 



REFERENCES 



Balss, H. 1914. Potamonidenstudien. Zoologische Jahrbiicher. Abteilung fiir 
Systematik, Geographie und Biologie der Thiere 37: 401-410. 

1929. Potamonidae au Cameroon. In: Contribution a I'etude de lafaune du 

Cameroun. Faune Colonies francaises 3: 115-129. 

1936. Beitrage zur Kenntnis der Potamidae (Siisswasserkrabben) des 

Kongogebeites. Revue du Zoologie et Botanie dAfrique 28: 65-204. 

Bott, R. 1955. Die Siisswasserkrabben von Afrika (Crust., Decap.) und ihre 
Stammesgeschichte. Annates du Musee Royal du Congo Beige. (Tervuren, 
Belgique,) C-Zoologie Serie III, III 1(3): 209-352. 

1959. Potamoniden aus West-Afrika. Bulletin de I'lnstitut Fondamental 

D'Afrique Noire, Serie A 21(3):994-1008. 

1964. Decapoden aus Angola unter besonderer Beriicksichtigung der 

Potamoniden (Crust. Decap.) und einem Anhang : Die Typen von Thel- 
phusa pelii Herklots 1861. Publicacoes ^ulturais da Companhia de Dia- 
mantes de Angola, Lisboa 69: 23-24. 

Capart, A. 1954. Revision des Types des especes de Potamonidae de l'Afriquc 
Tropicale conserves au Museum d'Histoire Naturelle de Paris. Volume 
Jubilaire Victor Van Strallen, Director de I'lnstitut Roy ale des Sciences 
Naturelles de Belgique, 1925-1934, II: 819-847. 

Chace, F. A. 1942. Scientific results of a fourth expedition to forested areas in 
eastern Africa, III: Decapod Crustacea. Bulletin of the Museum of Compara- 
tive Zoology, Harvard College 91(3): 1285-233. 

Cumberlidge, N. 1991. Sudanonautes kagoroensis, a new species of fresh-water 
crab (Decapoda: Potamoidea: Potamonautidae) from Nigeria. Canadian 
Journal of Zoology 69: 1938-1944. 

1993a. Redescription of Sudanonautes granulatus (Balss, 1929) (Potam- 
oidea, Potamonautidae) from West Africa. Journal of Crustacean Biology 
13(4): 805-816. 

1993b. Further remarks on the identification of Sudanonautes orthostylis 

(Bott. 1955), with comparisons with other species from Nigeria and Cam- 
eroon. Proceedings of the Biolological Society of Washington 106(3): 

514-522. 
De Man, J. G. 1901. Description of a new fresh-water Crustacea from the 

Soudan; followed by some remarks on an allied species. Proceedings of the 

Zoological Society of London: 94-104. 
Flower, S. S. 1931 . Notes on Fresh-water crabs in Egypt, Sinai, and the Sudan. 

Proceedings of the Zoological Society of London: 729-735. 
Herklots, J. A. 1861. Symbolae carcinologicae. Etudes sur la classe des 

Crustaces: 1-43. Leiden. 
Parisi, B. 1925. Un nuovo Potamonidi dell Abissinia. Atti Societi Italia Scienca 

Naturello, Museo civice Milano 61: 332-334. 
Milne Edwards, A. 1869. Revision du genre Thelphusa et description de 

quelques especes nouvelles faisant partie de la collection du Museum. 

Nouvelles Archives du Museum dHistoire naturelle, Paris 5: 161-191. 
Milne Edwards, H. 1853. Observations sur les affinities zoologiques et la 

classification naturelle des Crustaces. Annates des Sciences Naturelles, 

Zoologie, Paris, Serie 3, 20: 163-28. 
Monod, T. 1977. Sur quelques crustaces Decapodes africaines (Sahel. Soudan). 

Bulletin de Museum national d'Histoire naturelle, Paris 3, 500: 1201-1236. 

1980 Decapodes. In: Flore et Faune Aquatiques de I'Afrique Sahelo- 

Soudanienne, 1: 369-389. Ed. J-R. Durand and C. Leveque, ORSTOM, I.D 
T. 44, Paris. 

Nozais, J. P., Doucet, J., Dunan, J. & Assale N'Dri, G. 1980. Les paragoni- 
moses en Afrique Noire. A propos d'un foyer recent de Cote d'lvoire. 
Bulletin de la Societie de Pathologie exotique, 73: 155-163. 

Rathbun, M. J. 1904. Les crabes d'eau douce (Potamonidae). Nouvelles 
Archives du Museum d'Histoire naturelle (Paris) 6(4): 255-312. 



REDESCRIPTION OF AFRICAN FRESH-WATER CRAB 119 

1905. Les crabes d'eau douce (Potamonidae). Nouvelles Archives du (Paragonimus africanus und P. uterobilateralis) in West-Kamerun und 

Museum d'Histoire naturelle (Paris) 7(4): 159-322. Ost-Nigeria auf Grund von Untersuchungen an Siisswasserkrabben auf 

1921. The brachyuran crabs collected by the American Museum Congo Befall mit Metazerkarien. Tropenmedizin und Parasitologic 2$: 129-133. 

expedition 1909-1915. Bulletin of the American Museum of Natural History Voelker, J., Sachs, R., Volkmer, K. L., & Braband, H. 1975. On the 

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Bull. nat. Hist. Mus. Lond. (Zool.) 61(2): 121-137 



Issued 30 November 1995 



Association of epaxial musculature with 
dorsal-fin pterygiophores in acanthomorph 
fishes, and its phylogenetic significance 

RANDALL D. MOOI 

Milwaukee Public Museum, 800 West Wells St., Milwaukee, WI, U.S.A. 53233-1478 

ANTHONY C. GILL 

Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5 BD 

Synopsis. A survey of acanthomorphs reveals that epaxialis attachments to distal radials or the distal tips of 
proximal-middle pterygiophores have a relatively restricted distribution. Four basic morphotypes are recognized: Type 0- 
no distal insertions of epaxialis (lampridiforms, polymixiiforms, basal paracanthopterygians, zeiforms, beryciforms, 
smegmamorphs, pleuronectiforms and many perciforms); Type 1 - partially separate epaxialis slip(s) inserting on to 
dorsoposterior and dorsolateral processes of proximal-middle and/or distal radials (batrachoidids [Paracanthopterygii], 
scorpaeniforms, and among perciforms in blennioids, most cirrhitoids, apogonids, centrogeniids, latine centropomids, 
grammatids, haemulids, percids, serranids, champsodontids and cheimarrhichthyids); Type 2 - insertions of epaxialis to 
distal portions of pterygiophores without separate slips (possibly basal tetraodontiforms, various perciform taxa including 
callionymoids, notothenioids, zoarcoids, and some cirrhitids, labrids, percoids and trachinoids); Type 3 - completely 
separate slip of muscle dorsal to the main body of the epaxialis inserting on to anterior pterygiophore shaft with dorsal 
insertions on to more posterior spine-bearing pterygiophores, and the first ray-bearing pterygiophore, then becoming 
continuous with the supracarinalis posterior (percoid family Mullidae). Type is considered to be plesiomorphic, and the 
remaining morphologies apomorphic. Their phylogenetic significance is discussed in the context of other characters. 
Among our conclusions, the Scorpaeniformes is awarded subordinal status within the Perciformes, and the centropomid 
Latinae is given full familial status. 



INTRODUCTION 



Within the last five years, there has been renewed interest in 
higher relationships among acanthomorphs. The recent pub- 
lication of the Symposium on Phylogeny of Percomorpha 
(Johnson & Anderson, 1993) and other contributions 
(Stiassny, 1990; Stiassny & Moore, 1992) have shifted the 
focus somewhat from phylogenetic work on individual fami- 
lies to broader studies involving interrelationships of subor- 
ders and orders. Such studies are hampered by the difficulties 
inherent in examining large numbers of taxa, determining 
appropriate character complexes, and interpreting homolo- 
gies among the variation within those complexes. In many 
instances, characters are too complex or difficult to survey 
resulting in an incomplete understanding of their distribution 
within the included groups. During the course of investiga- 
tions on the relationships among pseudochromoids (sensu 
Mooi, 1990), we began surveying the relation of dorsal 
epaxial myology to the dorsal-fin pterygiophores. Dorsal 
epaxial myology appears to exhibit limited but sufficient 
variation over a broad range of taxa and the character states 
are simple enough to suggest it to be of high potential for 
phylogenetic analysis of higher relationships among acantho- 
morphs. 

Epaxial muscles, the dorsal component of the body muscu- 
lature, have received little attention from fish systematists. 
Although some studies have used variation in the anterior 
insertions of epaxial slips on to the head (e.g., Mooi, in press; 



Stiassny, 1990), few workers using myological features have 
surveyed this muscle group (Winterbottom, 1974a for a 
review). Mok et al. (1990) were the first to report variation in 
the relationship of the epaxial musculature with the dorsal-fin 
pterygiophores. They found that in two percoid families, the 
Grammatidae and Opistognathidae, the epaxial muscles 
insert on to the distal portions of anterior dorsal-fin pterygio- 
phores, and interpreted this as evidence for uniting the two 
taxa as sister groups. 

Our continuing studies on the phylogenetic positions of the 
Grammatidae, Opistognathidae and other pseudochromoid 
families have failed to provide corroborating evidence for a 
sister-group relationship between the Grammatidae and 
Opistognathidae. Moreover, a preliminary survey of epaxial 
morphology in perciforms revealed that the reportedly 
unique association of epaxial musculature with dorsal-fin 
pterygiophores described by Mok et al. (1990) is more widely 
distributed (Gill & Mooi, 1993: 333). Here we present an 
extensive survey of acanthomorph taxa, and show that, 
despite having a wider distribution than indicated by Mok et 
al., epaxial muscle/dorsal-fin pterygiophore associations nev- 
ertheless appear to be relatively restricted within acantho- 
morphs, and exhibit a number of recognizable morphologies. 
We explore the possible phylogenetic significance of the 
distribution of epaxial muscle insertions to dorsal-fin ptery- 
giophores and their homology. 



©The Natural History Museum. 1995 



122 



R.D. MOOI AND AC. GILL 



METHODS AND MATERIALS 



Epaxial musculature/dorsal-fin pterygiophore associations 
were studied in alcohol-stored specimens. An incision was 
made through the skin along the length of the fish between 
one third to one half the distance from the base of the dorsal 
fin and the midlateral septum. The incision ran from the skull 
to beneath the segmented-ray portion of the dorsal fin. The 
skin was either removed or folded dorsally to expose the 
underlying muscle. The inclinatores dorsales usually lifted up 
with the skin, or were removed individually to permit exami- 
nation of the epaxial muscles and the dorsal portions of the 
pterygiophores. When appropriate, epaxial fibres were 
traced anteriorly or posteriorly to ascertain their association 
with the supracarinalis muscle system. The insertions of 
epaxial fibres to pterygiophores were often re-examined on 
cleared and stained specimens and dry skeletons in the 
collections of the American Museum of Natural History, 
Milwaukee Public Museum, National Museum of Natural 
History, and The Natural History Museum. These specimens 
are not listed in Table 1. Illustrations of muscles were made 
with a camera lucida attached to a binocular dissecting 
microscope. 

Material dissected for myological observations is listed in 
Table 1. All species examined during the study are repre- 
sented in this list, although in many cases, multiple specimens 
were examined, occasionally from different lots, and some- 
times from museum collections other than those listed, par- 
ticularly the Field Museum of Natural History and Royal 
Ontario Museum. A complete list can be provided by the 
authors. Institutional codes follow Leviton et al. (1985). 



RESULTS 



Many (if not most) fishes have some epaxial fibre insertion 
near the proximal ends or near the middle of the dorsal-fin 
pterygiophores, whereas some taxa have epaxial muscle 
insertions on to the distal ends of the pterygiophores. We 
recognize four morphotypes of epaxial musculature, Types 
to 3. The consecutive numbering of the morphological types 
is not meant to imply character transformations; the morpho- 
types do not necessarily form a polarized transformation 
series. The vast majority of acanthomorph fishes (including 
putative basal taxa) exhibit an apparently primitive condition 
of the epaxial muscles, Type 0, with no attachment to the 
distal parts of the dorsal-fin pterygiophores, and with the 
musculature usually lying well below the dorsal tips of the 
pterygiophores (Fig. 1; Table 1). 

Of those taxa that do exhibit insertions on to the distal 
portions of the pterygiophores, epaxial fibres rarely insert on 
to pterygiophores other than those bearing non-segmented 
rays (spines), except where these ray elements are inter- 
preted as secondarily derived from spines (e.g., pseudochro- 
mids, zoarcoids, pleuronectiforms). In one scorpaeniform 
and a perciform genus as discussed below, and probably the 
paracanthopterygian Opsanus beta, there is insertion on 
primary ray-bearing pterygiophores. Among the taxa with 
dorsal insertions of epaxial fibres to spine-bearing pterygio- 
phores, there are three recognizable morphologies. Although 
these morphologies can be defined by specific taxa, their 



apparent differences become somewhat subjective at the ends 
of their respective morphological spectra. 

Type 1 is characterized by a partially separate muscle mass 
or series of slips of muscle fibres that insert on to the 
dorsoposterior and dorsolateral processes of the proximal- 
middle and/or distal radials of the pterygiophores. At least 
some fibres originate from the main body of epaxial muscle, 
but in extreme cases the dorsal muscle mass is detached 
between successive myosepta, and anteriorly there can be an 
elongate separate slip of muscle to an anterior pterygiophore 
(Fig. 2). We observed this morphotype in a single paracan- 
thopterygian species (Opsanus beta) (Fig. 3), blennioids, 
most cirrhitoids, seven percoid families (Apogonidae, Cen- 
trogeniidae, Centropomidae, Grammatidae, Haemulidae, 
Percidae, and Serranidae) and two trachinoid families 
(Champsodontidae and Cheimarrhichthyidae) among the sur- 
veyed perciforms (Figs 1, 4-5, 12-17), and all but one 
examined scorpaeniform (Figs 6-8) (Table 1). 

Among examined scorpaeniforms with Type 1, Normanich- 
thys crockeri exhibits a unique morphology (Fig. 8). The 
epaxial muscles insert on to the lateral processes of the first 
nine or ten pterygiophores as a separate mass of muscle. 
Posterior to the first dorsal fin, epaxial fibres attach directly 
to spineless (naked) pterygiophores and these fibres are not 
arranged as a separate muscle mass. A separate muscle mass 
is also present at the second dorsal fin, with insertions on to 
those pterygiophores bearing segmented rays. This gradually 
tapers out posteriorly and merges with the main body of 
epaxial muscle. Other scorpaeniform and percoid taxa exhib- 
iting Type 1 are quite consistent in their epaxial morphology; 
even among unusual taxa such as Aploactis (a scorpaeni- 
form), which has its dorsal fin placed far anteriorly over the 
skull, a narrow tendon extends from the epaxial to insert on 
to the third dorsal-fin pterygiophore. Differences arise in the 
degree of muscle separation, size of the anterior slip, on to 
which pterygiophores the muscle inserts, and on to which 
radials of the pterygiophores the insertion occurs (cf. Figs 
2-8). 

Species with a Type 2 epaxial morphology lack the obvious 
separation of the dorsal muscle bundle that inserts on to the 
distal portions of the pterygiophores, and the anterior slip is 
always absent. The insertions resemble sheets hanging on a 
clothes-line, draping from one pterygiophore to the next (Fig. 
9). In some taxa, the insertions are primarily via long 
tendons, and the muscle fibres themselves are relatively 
distant from the dorsal parts of the pterygiophores (Fig. 10). 
In most elongate taxa, the muscles are much more dorsally 
situated and the tendons are not as obvious. This morphology 
is found in various perciform taxa, including some members 
of the Cirrhitidae, Labridae, Percoidei, and Trachinoidei, 
and all of the few examined members of the Callionymoidei, 
Notothenioidei and Zoarcoidei (Table 1). The Tetraodonti- 
formes have a modified condition of this basic morphology 
which will be discussed below. 

A Type 3 epaxial morphology was found only in the family 
Mullidae (Fig. 11; Table 1). This type consists of a few 
epaxial fibres inserting on to an anterior pterygiophore 
relatively ventrally and on to a lateral wing along the main 
shaft rather than on to a dorsal posterolateral process. A 
completely separate slip of muscle sits dorsal to the epaxial 
muscle and inserts on to the anterior pterygiophore and only 
the posterior pterygiophores of the first dorsal fin. It extends 
further posteriorly, inserting on to the first pterygiophore of i 
the second dorsal, and gradually narrows posteriorly, insert- 






EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



123 



Table 1 List of taxa examined for epaxial muscle morphology. Morphological types: - no association with distal tips of dorsal-fin 

pterygiophores; 1 - partially separate muscle block or series of slips of muscle fibers that insert on to the dorsoposterior and dorsolateral 
processes of the proximal-middle and/or distal radials of the dorsal-fin ptergygiophores; 2 - insertions to the distal portions of the 
pterygiophores without an obvious separation from the main muscle body and with no separate anterior slip; 3 - completely separate slip of 
muscle dorsal to the main body of the epaxialis inserting on to an anterior pterygiophore shaft with dorsal insertions on to more posterior 
spine-bearing pterygiophores and the first pterygiophore bearing a segmented ray, then becoming continuous with the supracarinalis 
posterior. Orders are listed phylogenetically following Johnson & Patterson (1993); suborders, families, and species are listed alphabetically 
within orders. Incertae sedis genera of Percoidei are listed alphabetically among families. 



Taxon, Catalogue No., SL (mm) 



Type 



Taxon, Catalogue No., SL (mm) 



Type 



LAMPRIDIFORMES 
Veliferidae 

Veliferhypselopterus, AMNH 49575, 118.0 
POLYMIXIIFORMES 
Polymixiidae 

Polymixia lowei, AMNH 10116, 131.0 
PARACANTHOPTERYGII 
Aphredoderidae 

Aphredoderus sayanus , AMNH 50907, 53.5 
Batrachoididae 

Opsanus beta, AMNH 52369, 115.0 
Brotulidae 

Dinematichthys sp., USNM 297347, 88.5 
Gadidae 

Urophycisfloridanus, MPM 8409, 76.6 
Lotidae 

Lota lota, MPM 28380, 100.0 
Percopsidae 

Percopsis omiscomaycus , MPM 14060, 77.1 
ZEIFORMES 
Parazenidae 

Parazen pacificus, AMNH 29459, 116.5 
BERYCIFORMES 
Holocentridae 

Myripristispralinus, USNM 285922, 113.5 

Sargocentron vexillarus, MPM 30099, 56.7 
Trachichthyidae 

Hoplostethus mediterraneus, AMNH 49700, 1 17.0 
SYNBRANCHIFORMES 
Mastacembelidae 

Caecomastacembelus congricus, AMNH 6157, 145.0 

Mastacembelus armatus, FMNH 68484, 190.0 
ELASSOMATIFORMES 
Elassomatidae 

Elassoma okefenokee, MPM 28810, 20.5 

E. zonatum, MPM 14480, 28.5 
GASTEROSTEIFORMES 
Aulostomatidae 

Aulostomus maculatus, MPM 25182, 174.2 
Aulorhynchidae 

Aulorhynchm flavidus, AMNH 58939, 123.0 
Gasterosteidae 

Culaea inconstans, MPM 26675, 50.2 

Gasterosteus aculeatus, AMNH 37959, 54.0 
Macrorhamphosidae 

Macrorhamphosus scolopax, AMNH 84458, 85.5 
MUGILIFORMES 
Mugilidae 

Agonostomus monticola, MPM 13806, 41.0 

Mugilcephalus, USNM 152118, 93.2 

M. curema, MPM 6817, 56.4 
ATHERINIFORMES 
Atherinidae 

Atherinomorus stipes , MPM 30102, 53.4 

Menidia beryllina, MPM 30404, 63.0 
CYPRINODONTIFORMES 
Cyprinodontidae 

Cyprinodon variegatus, MPM 28940, 45.6 
Fundulidae 

Fundulus catenatus, MPM 15271, 70.8 



Poeciliidae 

Poecilia mexicana, MPM 8283, 55.4 
DACTYLOPTERIFORMES 
Dactylopteridae 

Dactylopterus volitans, USNM 307210, 59.5 
PERCIFORMES 
Acanthuroidei 
Acanthuridae 

Acanthurus triostegus, USNM 139750, 73.5 
Ephippididae 

Chaetodipterus zonatus, USNM 131415, 48.9 
Scatophagidae 

Scatophagusargus, BMNH 1976.4.13:2-7, 48.3 
Anabantoidei 
Anabantidae 

Anabas testudineus, AMNH 13766, 65.0 
Badidae 

Badis badis, USNM 89076, 26.8 
Belontiidae 

Belontia signata, USNM uncat., 64.4 

Macropodus operculars , AMNH 10641, 38.7 
Channidae 

Channa arga, AMNH 79406, 121.0 

C. obscurus, FMNH 70260, 136.0 
Nandidae 

Monocirrhus polyacanthiis, USNM uncat., 68.0 

Nandus nebulosus, USNM 230323, 47.7 

Polycentrus schomburgki, USNM 226071, 41.7 
Pristolepidae 

Pristolepisfasciata, USNM 305711, 75.7 
Blennioidei 
Blenniidae 

Enlomacrodus nigricans, MPM 18256, 55.4 

Hypleurochilus aequipinnis, MPM 23034, 28.2 

Ophioblennius atlanticus, MPM 24880, 52.4 

Scartella cristata, MPM 18231, 62.0 
Chaenopsidae 

Acanthemblemaria greenfieldi, MPM 24876, 30.4 

A. aspera, MPM 29983, 24.7 

Emblemariapandionis, BMNH 1938.2.2:2, 39.3 

Stathmonotus gymnodermis, MPM 24881, 23.6 

S. stahli, BMNH 1939.5.12:183-189, 18.8 
Clinidae 

Clinoporus biporosus, BMNH 1935.4.29:1-8, 89.5 

Clinuscottoides, BMNH 1887.4.16:3-5, 93.0 
Dactyloscopidae 

Dactyloscopus tridigitatus , MPM 24981, 60.0 

Gillellus uranidea, MPM 30131, 29.5 
Labrisomidae 

Labrisomus bucciferus, MPM 31163, 57.0 

L. nuchipinnis, MPM 18253, 82.0 

Malacoctenus gilli, MPM 24947, 49.1 

M. versicolor, MPM 22469, 36.0 

M. zonifer, BMNH 1861.8.13:33, 47.3 

Paraclinusfasciatus, MPM 25004, 36.2 

Starksia lepicoelia, MPM 29994, 23.5 
Tripterygiidae 

Enneanectes atrorus, MPM 30216, 21.0 

E. boehlkei, MPM 11572, 18.2 

E. pectoralis, MPM 22463, 26.5 

Lepidoblennius haplodactylus , BMNH 1890.9.23, 63.6 



124 



R.D. MOOI AND AC. GILL 



Taxon, Catalogue No., SL (mm) 



Type 



Taxon, Catalogue No., SL (mm) 



Type 



Callionymoidei 

Callionymidae 
Synchiropus splendidus , MPM uncat., 59.2 

Gobiesocidae 

Gobiesox strumosus, AMNH 86887, 58.5 
Carangoidei 

Carangidae 

Caranxlatus, MPM 13771, 119.0 
Oligoplites saurus, MPM 6364, 77.2 
Selene vomer, MPM 2273, 75.1 
Trachinotus rhodopus, MPM 6369, 107.0 

Nematistiidae 
Nematistius pectoralis, MPM 6367, 215.0 
Cirrhitoidei 

Aplodactylidae 
Aplodactylus punctatus, USNM 227298, 58.0 

Cheilodactylidae 

Cheilodactylus variegatus, USNM 77574, 58.0 
C. zonatus, USNM uncat., 73.5 

Chironemidae 

Chironemus marmoratus, ROM 40360, 125.4 

Cirrhitidae 
Amblycirrhitus bimacula, MPM 13509, 56.9 
Cirrhitichthys oxycephalus, ROM 60291, 55.2 
Cirrhitops hubbardi, ROM 59830, 64.5 
Cirrhitus pinnulatus, ROM 47702, 101.0 
Neocirrhitus armatus, ROM 59838, 44.1 
Paracirrhites arcatus, MPM 13587, 66.7 
Gobioidei 

Butidae 

Butis amboinensis , MPM uncat., 57.2 

Eleotrididae 
Eleotris pisonis, USNM 314448, 77.5 

Gobiidae 
Awaous taiasica, MPM 6811, 92.1 
Bathygobius soporator, MPM 18232, 80.0 

Odontobutidae 
Micropercops sp., AMNH 10441, 44.4 

Xenisthmidae 
Xenisthmus balius, USNM 326758, 26.1 
Labroidei 

Cichlidae 

Cichlasoma salvini, MPM 22851, 48.8 
Etroplus suratensis, USNM 301169, 69.5 

Embiotocidae 

Rhacochilus argyrosomus, USNM 53969, 45.7 

Labridae 
Bodianus bilunulatus , MPM 13518, 76.3 
B. diana, USNM 232355, 52.0 
Cheilinus oxycephalus, USNM 262088, 62.1 
Cheilio inermis, MPM 13369, 88.6 
Choerodon graphicus, USNM 218548, 60.2 
Coris variegata, USNM uncat., 86.0 
Halichoeres bivitattus, MPM 8524, 73.6 
Hemipteronotus martinicensis, USNM 37075, 85.0 
Labroides dimidiatus, MPM uncat., 51.7 
Sparisoma rubripinnis, MPM 30040, 62.6 
Tautoga onitis, USNM 118352, 53.2 
Thalassoma duperryi, MPM 13403, 77.7 
T. lutescens, USNM 112696, 82.0 

Pomacentridae 
Abudefdufsaxatilis, USNM 275040, 63.5 
Amphiprion melanopus, USNM 309519, 68.0 
Lepidozygus tapeinosoma, USNM 275893, 51.5 
Notothenioidei 

Nototheniidae 
Notothenia sima, AMNH 5003, 82.5 



Percoidei 
Acropomatidae 

Malakichthys griseus, USNM 184143, 60.2 
Ambassidae 

Ambassis sp., USNM 223376, 37.8 

Chanda ranga, BMNH 1938.12.22:132-141, 40.0 
Apogonidae 

Apogon angustatus, USNM 261750, 57.0 

Apogonichthys ocellatus, AMNH 33808, 43.0 

Cheilodipterus macrodon, AMNH 33714, 68.0 
Bathyclupeidae 

Bathyclupea malay ana, BMNH 1982.9.6:106-107, 117.0 
Callanthiidae 

Callanthias australis, AMS 1.18709-002, 88.0 

C. platei, USNM 307594, 93.0 
Caproidae 

Antigoniaeos, MPM 13598, 71.3 

Caprosaper, BMNH 1963.5.14:230-239, 43.5 
Centrarchidae 

Lepomis gibbosus, MPM 28675, 56.2 

Micropterus salmoides, MPM 20246, 62.2 
Centrogeniidae 

Centrogenys vaigensis, USNM 245612, 70.0 
Centropomidae 

Centropomus armatus, USNM uncat., 108.7 

C. ensiferus, ROM 61657, 47.7 

C. pectinatus, ROM 61664, 61.0 

C. undecimalis, ROM 40904, 118.5 
Cepolidae 

Cepola rubescens, BMNH 1970.4.18:3, 438.0 

Owstonia totomiensis, BMNH 1986.10.6:61, 91.0 
Chaetodontidae 

Chaetodon multicinctus , MPM 13556, 89.7 

C. miliaris, MPM 13466, 56.0 
Datnioides quadrifasciatus , USNM 297256, 120.0 
Dinolestidae 

Dinolestes lewinii, USNM 59932, 138.5 
Enoplosidae 

Enoplosus armatus, USNM 48808, 77.5 
Gerreidae 

Eucinostomus gula, USNM 43216, 45.0 
Glaucosomatidae 

Glaucosoma scapulare , AMS 1.27325-002, 45.1 
Grammatidae 

Gramma linki, AMNH 35776, 36.3 

G. loreto, MPM 15612, 50.4 

Lipogramma anabantoides , AMNH 33061, 16.8 

L. trilineata, FMNH 95658, 24.2 
Haemulidae 

Anisotremus scapularis, USNM 127982, 55.8 

Conodon nobilis, MPM 13778, 104.5 

Haemulon aurolineatum , MPM 23228, 64.2 
Hapalogenys sp., BMNH 1984.1.13:76-82, 55.0 
Hemilutjanus microphthalmus , USNM 77623, 138.0 
Kuhliidae 

Kuhlia rupestris, USNM 184110, 82.0 
Kurtidae 

Kurtus gulliveri, USNM 217310, 128.0 
Kyphosidae 

Girella tricuspidata, USNM 269547, 99.5 

Sectatoroxyurus, USNM 288880, 75.1 
Lactariidae 

Lactarius delicatulus, BMNH 1895.2.28:51, 87.0 
Lateolabrax japonicus , USNM 64630, 87.0 
Latidae 

Lates albertianus, ROM 26537, 141.1 

L. calcarifer, BMNH 1898.12.24:2, 113.5 

L. mariae, ROM 28140, 125.2 

L. niloticus, BMNH 1907.12.2:2959-2968, 48.5 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



125 



Taxon, Catalogue No., SL (mm) 



Type 



Taxon, Catalogue No., SL (mm) 



Type 



Psammoperca waigiensis, BMNH 1933.3.11:312, 118.0 
Lethrinidae 

Lethrinus lentian, BMNH 1932.7.29:82-83, 70.8 
Lobotidae 

Lobotes surinamensis, USNM 156452, 46.6 
Lutjanidae 

Lutjanus griseus, MPM 8542, 48.1 

L. kasmira, USNM 183109, 98.8 
Malacanthidae 

Caulolatilusaffinis, USNM 211424, 104.5 
Monodactylidae 

Monodactylus argenteus, MPM 31026, 33.2 
Moronidae 

Dicentrarchus labrax, BMNH 1987.2.22:1-12, 42.5 

Morone chrysops, MPM 4569, 78.3 
Mullidae 

Mulloidichthys martinicus, MPM 5321, 86.0 

Parupeneus multifasciatus , MPM 13530, 79.0 

Upeneus maculatus, USNM 126150, 76.0 
Nemipteridae 

Pentapodusporosus, BMNH 1984.8.20:27, 62.0 
Notograptidae 

Notograptus sp., USNM 173797, 174.0 
Opistognathidae 

Opistognathus maxillosus, MPM 30098, 98.3 
Oplegnathidae 

Oplegnathusfasciatus, BMNH 1905.6.6:154-161, 126.0 
Ostracoberycidae 

Ostracoberyx sp., USNM 307282, 83.0 
Pempherididae 

Parapriacanihus ransonneti, MPM 31028, 58.2 

Pempheris schomburgki , FMNH 93774, 52.3 
Percichthyidae 

Percichthysaltispinnis, USNM 163382, 70.1 

Percilia gillissi, USNM 84341, 60.0 
Percidae 

Etheostoma nigrum, MPM 22420, 56.3 

Percaflavescens, MPM 25409, 79.0 

Percina maculata, MPM 20880, 76.7 

Stizostedion canadense, MPM 6015, 86.7 
Pholidichthyidae 

Pholidichthys leucotaenia, USNM 289924, 77.0 
Plesiopidae 

Acanthoclinus fuscus, USNM uncat., 77.7 

Assessor macneilli, USNM 295659, 40.5 

Belonepterygion fasciolatum , USNM 273813, 34.0 

Calloplesiops altivelis, USNM 261333, 60.4 

Plesiops coeruleolineatus , USNM uncat., 45.5 

Trachinops taeniatus, USNM 274580, 37.2 
Polynemidae 

Polydactylus approximans, USNM uncat., 60.2 
Polyprionidae 

Polyprion americanus, BMNH 1845.6.22:11, 190.0 
Pomacanthidae 

Centropyge bispinosus, USNM 259696, 61.5 
Pomatomidae 

Pomatomussaltatrix, BMNH 1967.2.1:80-85, 74.7 
Priacanthidae 

Priacanthus hamrur, USNM 289285, 72.5 
Pseudochromidae 

Haliophis guttatus, USNM uncat., 137.5 

Labracinus cyclophthalmus, USNM 309335, 85.8 

Ogilbyina queenslandiae , USNM 290792, 59.3 

O. salvati, USNM 278149, 50.3 

Pseudochromis elongatus, USNM 290784, 35.6 

P. fuscus, USNM 290345, 56.5 

'Pseudochromis' diadema, USNM 290591, 32.9 
Sciaenidae 

Aplodinotus grunniens, MPM 16805, 66.4 



1 Bairdiella chrysura, MPM 8954, 100.0 2 
Cynoscion regalis, MPM 8969, 94.9 2 

Equetus acuminatus, MPM 8522, 90.1 2 

Leiostomus xanthurus, MPM 8934, 87.1 

Menlicirrhus littoralis, MPM 8443, 68.7 2 

Micropogonias undulatus, USNM 142675, 67.5 

Sciaenops ocellata, MPM 30424, 61.5 2 

Stellifer lanceolatus , MPM 8936, 57.9 2 

Serranidae 
Alphestes afer, USNM 235696, 89.0 

Anyperodon leucogrammus , USNM uncat, 103.5 
Centropristis philadelphicus, USNM 142813, 75.8 

Chelidoperca sp., USNM 322386, 80.0 
Diplectrum macropoma, USNM 21 1397, 129.0 

Epinephelus merra, USNM 309689, 75.5 

Grammistes sexlineatus, USNM 166994, 62.0 
3 Hypoplectrodes sp. , USNM 19881 1 , 67.5 

3 H. maccullochi, USNM 42039, 102.1 

3 Hypoplectrus puella , MPM 2346 1 , 92 . 3 

Liopropoma rubre, MPM 25083, 41.0 
L. sp., USNM 322359, 76.5 

Mycteropercaflorida, USNM 176238, 59.7 

2 Niphon spinosus, USNM 59739, 130.0 
Paralabrax clathratus, USNM 54807, 53.0 

2 Plectranthias nanus, USNM 288812, 24.9 

Pseudanthias taeniatus, USNM 279782, 54.5 

P. thompsoni, USNM uncat., 118.0 

Pseudogramma sp., USNM 245340, 42.8 

Serranus hepatus, USNM uncat., 73.0 

5. tigrinus, MPM 30183, 58.3 

Sillaginidae 

Sillago cilliata, USNM 207647, 72.6 2 

Sinipercidae 

Coreoperca kawamebari, USNM 71331, 32.3 2 

Sinipercachautsi, USNM 87082, 93.2 2 
Sparidae 

1 Diplodus bermudensis, MPM 18228, 76.5 
1 Symphysanodontidae 

1 Symphysanodon berryi, USNM 289922, 85.5 

1 Synagrops bella, USNM 156955, 75.5 2 
Terapontidae 

2 Terapon jarbua, USNM uncat., 80.0 
Toxotidae 

2 Toxotes jaculator, USNM uncat., 45.0 

Scombroidei 

Scombridae 

Scomber japonicus,AMNH 74945, 149.0 

Sphyraenidae 

Sphyraena barracuda, MPM 11496, 93:0 

Trichiuridae 
Trichiurus lepturus , MPM 8430, 316.0 

Scorpaenoidei 
Agonidae 

Agonus decagonus, USNM 165146, 132.5 1 

Anoplopomatidae 

Anoplopoma fimbriata, USNM 208296, 123.0 1 

Aploactinidae 

Aploactis milesii, USNM 59980, 121.0 1 

Bathylutichthyidae 

Bathylutichthys taranetzi, BMNH 1994.7.22:1, 100.5 

2 Caracanthidae 

2 Caracanthus maculatus, USNM 140990, 34.5 1 

2 Congiopodidae 

2 Alertichthys blacki, USNM 318386, 80.0 1 

2 Cottidae 

2 Ascelichthysrhodorus, BMNH 1881.3.22:57-63, 50.0 1 

2 Centrodermichthys analis, BMNH 1890. 1 1 . 15: 105, 56.7 1 

Cottus bairdi, MPM 5878, 70.8 1 



126 



R.D. MOOI AND A.C. GILL 



Taxon, Catalogue No., SL (mm) 



Type 



Taxon, Catalogue No., SL (mm) 



Type 



C. perplexus, USNM 258839, 51.5 

Icelus hamatus, BMNH 1877.5.13:7-9, 60.3 

Myoxocephalus scorpis, BMNH 1981.2.10:629, 50.5 

Taurulus bubalis, BMNH 1981.2.20:776-794, 38.5 
Cottocomephoridae 

Cottocomephorus grewingkii, USNM 222075, 100.0 
Cyclopteridae 

Cyclopterus lumpus, USNM 197582, 83.8 
Hoplichthyidae 

Hoplichthys langsdorfi, USNM 309447, 123.0 
Liparididae 

Liparis agassizii, USNM 74697, 117.5 

L. liparis, BMNH 1971.2.16:1757-1760, 99.5 

Paraliparis hystrix, BMNH 1992.10.20:43-48, 87.8 
Normanichthyidae 

Normanichthys crockeri, USNM 176507, 56.7 
Pataecidae 

Aetapcus maculatus, BMNH uncat., 118.0 

Pataecusfronto, BMNH 1914.8.20:282, 159.0 
Platycephalidae 

Thysanophrys japonica, USNM 70735, 119.0 
Psychrolutidae 

Cottunculus microps, BMNH 1981.3.16:550-553, 87.5 

Psychrolues zebra, BMNH 1986.7.12:193, 41.5 
Scorpaenidae 

Pterois radiata, USNM 140491, 64.8 

Scorpaena sonorae, USNM 59463, 67.6 

Sebastes alutus, USNM 72461, 80.0 
Triglidae 

Bellator militaris, USNM 1 14793, 83.0 1 

Stromateoidei 
Stromateidae 

Peprilus burti, MPM 829 1 , 92 . 4 

Trachinoidei 
Ammodytidae 

Ammodytes americanus, AMNH 36780, 72.0 

A. hexapterus, FMNH 80613, 106.0 

A. lanceolatus, FMNH 34257, 177.0 

A. personam, USNM 104499, 86.0 

Champsodontidae 

Champsodon sp., USNM 150556, 64.2 1 

Cheimarrhichthyidae 

Cheimarrichthys fosteri, AMNH 98274, 71.0 1 

Chiasmodontidae 

Chiasmodon sp., USNM 186139, 110.0 

Dysalotus alcocki, MCZ 60806, 1 12.0 



Kali normani, USNM 207614, 159.6 

Pseudoscopelus sp. , ARC 8706465, 57.0 

Creediidae 

Crystallodytes cookei, FMNH 63619, 41.0 2 

Limnichthys fasciatus , AMNH 57282 , 45 . 5 2 

Percophididae 

Bembrops anatirostris , AMNH 83323, 170.0 2 

B. gobioides, FMNH 67070, 112.0 2 

Pinguipedidae 

Parapercis cephalopunctatus, FMNH 72471, 108.0 2 

P. montillai, AMNH 50585, 94.0 2 

Uranoscopidae 

Kathetostoma albiguttata, FMNH 45246, 99.0 2 

Uranoscopus sp., USNM 113145, 80.0 2 

Zoarcoidei 

Anarhichadidae 

Anarrhichthys ocellatus, USNM 57832, 585.0 2 

Bathymasteridae 

Bathymaster signatus, USNM 24004, 130.0 2 

Ronquilus jordani , MPM 394, 133.1 2 

Stichaeidae 

Anoplarchus purpurescens, MPM 366, 94.2 2 

Zoarcidae 

Lycodopsis pacifica, MPM 408, 117.3 2 

PLEURONECTIFORMES 
Achiridae 

Achirus lineatus, MPM 13783, 95.0 

Bothidae 

Bothus lunatus, MPM 24885, 1 14.0 

Cynoglossidae 

Symphurus plagiusa, MPM 10525, 113.0 

Paralichthyidae 

Citharichthys spilopterus , MPM 895 1 , 1 03 . 

Pleuronectinae 

Pseudopleuronectes americanus, AMNH 33401, 119.5 

Psettodidae 

Psettodes erumei, BMNH 1904.5.25: 197-8, 83.4 

Poecilopsettinae 

Poecilopsetta hawaiiensis, MPM 13604, 106.3 

Samarinae 

Samariscus triocellata, MPM 13387, 67.0 

TETRAODONTIFORMES 
Balistidae 

Rhinecanthus aculeatus, AMNH 50748, 52.5 2 

Monacanthidae 

Pervagorspilosoma, MPM 13528, 78.4 2 



ing on to no other pterygiophores, but becoming continuous 
with the supracarinalis posterior. With such minimal fibre 
sharing of this elongate separate slip with the epaxial, it 
appears that the separate slip is likely to be a modified 
supracarinalis posterior or supracarinalis medius. Although 
no other taxon was found exhibiting this morphology, a few 
taxa do have a tendon extending to the supracaranalis poste- 
rior from the last fibres of the epaxial section that inserts on 
to the pterygiophores. We observed this condition in the 
cirrhitid Paracirrhites arcatus, some labrids (including Spari- 
soma and Halichoeres), as well as some blennioids. This 
tendon can be difficult to detect, and could be present in 
other taxa, although no trace of this feature was found in 
serranids or scorpaeniforms. 



DISCUSSION 



The insertion of epaxial muscle on to dorsal-fin pterygio- 
phores is more widespread and exhibits more variation than 
has been previously reported. The distribution of the various 
recognized morphotypes suggests that it could have some 
value for estimating phylogenetic relationships. The most 
commonly encountered morphology among acanthomorphs, 
that of no epaxial insertions to dorsal posterolateral processes 
of dorsal-fin pterygiophores (Type 0), appears to be the 
primitive condition, as it occurs in all basal acanthomorph 
taxa (sensu Johnson & Patterson, 1993). Dorsal epaxial/ 
pterygiophore associations are absent from groups such as 
lampridiforms, polymixiiforms, basal paracanthopterygians, 
beryciforms, and smegmamorphs, as well as pleuronectiforms 
(Table 1). Hence, Types 1-3 are apomorphic at some level. 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



127 




Fig. 1 Type epaxial muscle as exemplified by Morone chrysops (MPM 4569, 78.8 mm SL). Inclinatores dorsales removed to expose medial 
muscles. Note that there is no insertion of the epaxial musculature to the distal tips of the pterygiophores. Margins of muscle demarcated by 
thicker lines; bone stippled. DD, depressores dorsales; DI, distal radial; ED, erectores dorsales; EPAX, epaxialis; PM, proximal-middle 
radial; SCA, supracarinalis anterior; SCP, supracarinalis posterior; SN, supraneural; SP, spines; SR, segmented ray. Scale bar = 10 mm. 



EPAX 




Fig. 2 Type 1 epaxial muscle as exemplified by Epinephelus merra (USNM 246689, 96.5 mm SL). Inclinatores dorsales removed to expose 
medial muscles. Note the separate slip of epaxial muscle which inserts dorsally on to the second pterygiophore (directly behind the second 
spine) and the additional insertions on to pterygiophores 3-8. Abbreviations and other methods of presentation as in Fig. 1. Scale bar = 5 
mm. 



Among these apomorphic morphologies. Type 1 is the 
easiest to characterize and identify. It is found among a 
restricted group of perciform families and is considered the 
exclusive epaxial/pterygiophore association of the Scorpaeni- 
formes (see below for discussion of Type condition in 
Bathylutichthys). A scorpaeniform sister group has remained 
elusive and this has been a serious barrier to understanding 
internal relationships of the Scorpaeniformes. The presence 
of a derived Type 1 epaxial morphology in the Scorpaeni- 
formes and a small subset of the Perciformes suggests that the 
sister group of the Scorpaeniformes possibly lies within this 
subset. Percoid taxa rarely have been considered candidates 
for such status, although seven percoid families exhibit a 
Type 1 morphology (Table 1; Figs 2, 4-5). Despite generally 
being recognized as a heterogeneous and probably non- 
monophyletic assemblage (e.g. Johnson, 1984), percoids 
have been referred to as a single, identifiable taxonomic 



SP1 



PM SR1 V 




Fig. 3 Type 1 epaxial musculature in the batrachoidid Opsanus 
beta (MPM 8919, 139.5 mm SL). Insertions to the 11th dorsal-fin 
pterygiophore. SP1, first spine; SRI, first segmented ray; other 
abbreviations and methods of presentation as in Fig. 1. Scale bar 
= 10 mm. 




Fig. 4 Type 1 epaxial musculature in three percoids: a, Apogon 
maculatus (MPM 24869, 64.6 mm SL), Apogonidae, with 
insertions to the first through third pterygiophores; b, 
Centrogenys vaigiensis (USNM 150792, 53.4 mm SL), 
Centrogeniidae, with insertions to the first through seventh 
pterygiophores; c, Perca flavescens (MPM 25409, 79.2 mm SL), 
Percidae, with insertions to the fourth through ninth 
pterygiophores. Abbreviations and other methods of presentation 
as in Figs 1,3. Scale bars = 5 mm. 



128 



R.D. MOOI AND A.C. GILL 



,SC /SN SP1 



EPAX 



rPM + DI 




Fig. 5 Type 1 epaxial morphology with extreme fibre separation from the main epaxial body of the epaxial muscle slip inserting on to 

pterygiophores in Haemulon aurolineatum (MPM 23228, 64.2 mm SL). SP1, first dorsal-fin spine; SRI, first segmented dorsal-fin ray; other 
abbreviation and methods of presentation as in Figs 1, 3. Scale bar = 5 mm. 



group for so long that they have been reified; in practice, 
most systematists regard the Percoidei as a bona fide taxon. 
As a consequence ichthyologists have rarely examined taxa 
from among the Percoidei as potential relatives of non- 
percoid taxa (exceptions include Johnson, 1984, 1986, 1993; 
Tyler et al. 1989), and few characters have been identified to 
suggest a relationship among percoids and scorpaeniforms, at 
least in part because few researchers have looked. These 
same problems apply to the more inclusive Perciformes, for 
which no satisfactory definition exists and membership is 
often questionable; families considered perciforms are rarely 
examined as either sister taxa or possible members of other 
acanthomorph orders (although see Johnson & Patterson, 
1993) because, in practice, the Perciformes is treated as a 
monophyletic taxon. 

Several additional characters suggest that a relationship 
between scorpaeniforms and at least some of the 'percoids' 
with a Type 1 epaxial morphology is worthy of consideration. 
For example, some larval serranids (particularly anthiines) 
bear at least a superficial resemblance to larval scorpaeni- 
forms, with suspensorial and cranial bones highly orna- 
mented by spines and ridges (cf. Figs and descriptions in: 
Baldwin, 1990; Johnson, 1984; Kendall, 1984; Washington et 
al., 1984). Moreover, the general physiognomies of many 
adult serranids bear striking resemblances to certain scor- 
paeniforms. Although general similarities do not provide the 
necessary evidence for relationship, they hint that there 
might be more evidence than shared epaxial morphology; we 
feel it is premature to dismiss these similarities as being due 
to convergence before relationships are better understood. 

The occurrence of Type 1 epaxial morphology in few 
non-percoid perciform taxa (blennioids, some cirrhitoids and 
some trachinoids) suggests that these should also be included 
in a search for a scorpaeniform sister group, or considered for 
inclusion among scorpaeniforms (Mooi & Johnson, in prep). 
For example, blennioids also resemble scorpaeniforms in 
having the supratemporal sensory canal enclosed by the 
parietal (except in most tripterygiids where the cephalic 
sensory canals are incompletely enclosed by bone; Springer, 
1993:487 and pers. obs.). This condition is found in several 
other perciform taxa, including at least some zoarcoids (sensu 
Anderson, 1984; Travers, 1984b; all 'zoarceoids' according to 
Gosline, 1968:46), some pseudochromids (Gill, in prep.), and 
mastacembeloid synbranchiforms (Travers, 1984a), but these 
taxa do not have a Type 1 epaxial morphology. Champsodon- 
tids more closely resemble scorpaeniforms in having a serrate 
ridge overlying the canal (Johnson, 1993:14; Mooi & 
Johnson, in prep.), as well as Type 1 epaxials. Although 
blennioid parietals lack the serrate ridge or spine over the 
canal, the possibility of a blennioid/scorpaeniform relation- 



ship deserves further study. Certain cottoids closely resemble 
blennioids in dorsal gill arch morphology, notably in lacking 
an interarcual cartilage, and in having only a single 
infrapharyngobranchial (infrapharyngobranchial 3), which 
articulates posteriorly with epibranchials 3 and 4 (e.g., com- 
pare cottoids in Rosen & Patterson, 1990: figs 34A, C and 
Yabe, 1985: figs 23, 24E with blennioids in Rosen & Patter- 
son, 1990: figs 33A-B, 37, 38C-D and Springer, 1993: fig. 1). 
Members of the cottoid family Liparididae further resemble 
blennioids in lacking an uncinate process on epibranchial 1 
(Kido, 1988: figs 12A-D). 

Johnson & Patterson (1993: 591) found no evidence to 
indicate a 'pre-perciform' position for scorpaeniforms, and 
considered ranking them at the subordinal level within the 
perciforms, 'if only to stimulate the search for characters 
justifying their individuality.' We concur with Johnson & 
Patterson's proposal and award subordinal ranking for the 
Scorpaeniformes, as the Scorpaenoidei, within the Perci- 
formes. In addition to the justification provided by Johnson 
& Patterson (1993), we believe this action will be a major step 
forward in diagnosing a monophyletic Perciformes. There is 
no contrary evidence for maintaining the two orders as 
separate, and the epaxial morphology and other evidence 
noted above suggests that the Perciformes is non- 
monophyletic without the inclusion of the Scorpaeniformes. 

The almost universal occurrence of Type 1 epaxial muscles 
in the Scorpaenoidei has implications for its composition. It 
casts doubt on the inclusion of the Dactylopteridae and 
Bathylutichthyidae within the suborder, as neither family has 
insertions of epaxial muscle to dorsal-fin pterygiophores 
(Table 1). Johnson (1993: 7) also raised doubts about a 
relationship between dactylopterids and scorpaenoids based 
on the absence of a bone-enclosed supratemporal canal and 




Fig. 6 Type 1 epaxial musculature in a 'primitive' scorpaeniform 
Anoplopoma fimbriata (USNM 208296, 122.2 mm SL). Note the 
separate slip of epaxial muscle to the third dorsal-fin 
pterygiophore, and other insertions of epaxial to as far posteriorly 
as the ninth pterygiophore. Abbreviations and other methods of 
presentation as in Fig. 1. Scale bar = 5 mm. 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



129 



lack of parietal spines; Johnson & Patterson (1993: 579) 
considered and rejected a relationship between dactylop- 
terids and gasterosteiforms. The monotypic family Bathylu- 
tichthyidae was recently erected by Balushkin & 
Voskoboynikova (1990) and placed in the Scorpaeniformes 
(our Scorpaenoidei) largely on the basis of trend characters 
variably shared with some cottoid taxa. Although Bathylu- 
tichthys could have secondarily lost Type 1 epaxial insertions, 
its position in the Scorpaenoidei should be regarded as 
provisional. The condition of the parietal and supratemporal 
canal in Bathylutichthys could be informative, but requires 
investigation. 

Conversely, Mandrytsa (1991) has recently questioned the 
inclusion of the Pataecidae in the Scorpaenoidei (his Scor- 
paeniformes) based on a study of cephalic lateral-line struc- 
ture. We have examined specimens of two of the three 
pataecid genera (Aetapcus and Pataecus; Table 1) and found 
that they have a typical scorpaenoid Type 1 arrangement of 
their epaxial musculature, corroborating their current posi- 
tion in the suborder. Ishida's (1994) more detailed analysis of 
various myological and osteological characters also conclu- 
sively nests pataecids within the Scorpaenoidei (as the sister 
group of the Aploactidae). 

Winterbottom (1993) suggested a relationship of gobioids 
with the scorpaenoid family Hoplichthyidae, but this is not 
supported by our observations. Gobioids have no association 
of epaxial muscle with distal portions of the dorsal-fin ptery- 
giophores, whereas hoplichthyids exhibit a typical scor- 
paenoid Type 1 pattern. 

The shared Type 1 morphology in a subset of perciforms 
(blennioids, some cirrhitoids, Apogonidae, some Centropo- 
midae, Centrogeniidae, Champsodontidae, Cheimarrhich- 
thyidae, Grammatidae, Haemulidae, Percidae, and 
Serranidae) implies that closer relationships might exist 
among these taxa than are presently recognized (cf. Figs 2, 
4-5, 12-17). The enigmatic family Centrogeniidae is an 
interesting example because its nomenclatural history reflects 
the possible relationships suggested by epaxial morphology. 
Centrogenys vaigiensis, the single included species, and/or its 
junior synonyms, has variously been classified as a scorpaeni- 
form (e.g., Day, 1875; Fowler & Bean, 1922), a serranid 
(e.g., Jordan, 1923; Weber & de Beaufort, 1931; Paxton et 
al., 1989), or has been suggested to bear a superficial 
resemblance to cirrhitids (Gosline, 1966; Nelson, 1984). 
Although Centrogenys does not fit comfortably into any of 
these taxa as they are currently diagnosed, the similar Type 1 
epaxial musculature suggests that a detailed anatomical com- 
parison could provide considerable insight into their interre- 
lationships. 

In the Centropomidae, we found that extant members of 



the subfamily Latinae (Lates, Psammoperca) have a modified 
Type 1 epaxial morphology where the muscle insertions to 
the pterygiophores are separate from the main epaxial body, 
but are below the spine/pterygiophore articulation (Fig. 12); 
this arrangement could also be described as a modified Type 
morphology with a more dorsal position of the normally 
proximal insertions. The Centropominae (Centropomus) dif- 
fer in lacking such dorsal epaxial insertions to dorsal-fin 
pterygiophores (Type 0) (Table 1). Greenwood (1976) 
hypothesized the monophyly of the Centropomidae, with its 
two subfamilies as sister taxa, on the basis of two synapomor- 
phies: pored lateral-line scales extending to posterior margin 
of caudal fin, and neural spine of second vertebra markedly 
expanded in an 'anteroposterior direction.' Pored lateral-line 
scales extend well on to the caudal fin in many acanthomorph 
fishes, and reach, or nearly reach, the posterior margin of the 
fin in several families, including sciaenids (Greenwood, 
1976), moronids (G.D. Johnson, pers. comm.), most pem- 
pheridids, rhyacichthyids (Springer, 1983) and polynemids. 
Therefore, this character does not provide convincing evi- 
dence of relationship, and may be plesiomorphic within 
perciforms. We also are not convinced that Greenwood's 
second character (also noted by Gosline, 1966), expansion of 
the second neural arch, is homologous in centropomines and 
latines. In adult centropomines (see Fraser, 1968: 455 for 
discussion of ontogenetic variation), the second neural spine 
is broadly expanded over most of its length (resulting in a 
truncated or rounded distal tip to the spine) and closely 
applied to the first neural spine, which is narrow and sharply 
pointed (see Fraser, 1968: fig. 14; Greenwood, 1976: fig. 25d; 
Rosen, 1985: fig. 39B). In contrast, the anterior neural spine 
morphology of the latines does not differ markedly from the 
conditions found in various basal perciforms; the second 
neural spine is only expanded proximally, and is not closely 
applied to the first neural spine (see Greenwood, 1976: figs 
25a-c). Given the lack of convincing synapomorphies to unite 
the subfamilies Latinae and Centropominae, and considering 
the differences in epaxial morphology (as well as various 
other anatomical differences listed by Greenwood, 1976), 
there is no justification for placing them in a single family. 
Based on their modified Type 1 epaxial morphology, we here 
remove the African/Indo-Australian genera Lates and Psam- 
moperca from the Centropomidae to a separate family, 
Latidae. Hypopterus (Western Australia) and Eolates (Italy 
[Monte Bolca]), included as latines by Greenwood (1976), 
presumably also belong to the newly created Latidae. Green- 
wood (1976) considered Psammoperca macroptera, the type 
species of Hypopterus, to be a synonym of P. waigiensis, the 
single species he recognized in Psammoperca; however, 
recent authors (e.g., Allen & Swainston, 1988: 62; Paxton et 



SCA 




Fig. 7 Type 1 epaxial musculature in the scorpaeniform Pterois radiata (USNM 140493, 63.3 mm SL). Note the insertion of the epaxial 
muscle on to elements of the second pterygiophore and those posterior to the ninth pterygiophore. Abreviations and other methods of 
presentation as in Fig. 1. Scale bar = 5 mm. 



130 



R.D. MOOI AND AC. GILL 



,PM ,DI 




Fig. 8 An unusual Type 1 epaxial morphology in Normanichthys crockeri (USNM 176507, 63.4 mm SL). I - portion of the epaxial that 
inserts on to the anterior pterygiophores largely separate from the main body of the epaxial, with only a few fibres shared from each 
myoseptal section. The exceptions are the insertions on the two anteriormost pterygiophores which have many of their fibres originating 
from the main epaxial muscle body. II - portion inserting on to pterygiophores that is not separate from the main epaxial body. Ill - 
portion inserting on to the ptergygiophores bearing segmented rays, is mostly separate until just beyond the last ray where it merges with 
the rest of the epaxial musculature. RPT, rayless pterygiophore; other abbreviations and methods of presentation as in Figs 1, 3. Scale bar 
= 5 mm. 



al., 1989: 482) have regarded Hypopterus as a valid, mono- 
typic genus. We provisionally retain the Centropomidae 
(Centropomus only) until its relationships are better under- 
stood. 

The Trachinoidei as defined by Pietsch & Zabetian (1990) 
exhibit a variety of epaxial morphologies (Table 1). 
Ammodytids and chiasmodontids have Type 0, champsodon- 
tids and cheimarrichthyids have Type 1, and Type 2 is found 
in the creediids, percophidids, pinguipedids and ura- 
noscopids. Considering the discussion by Johnson (1993: 
13-15), this epaxial character distribution casts further doubt 
on the integrity of this suborder as currently constituted. 
Although it seems likely that the epaxial morphologies as 
defined here have evolved more than once among acantho- 
morphs, it is difficult to reconcile their distribution with the 
phylogeny provided by Pietsch & Zabetian (1990). One of 
their phylogenetic hypotheses is a sister group relationship 
between the Chiasmodontidae and the Champsodontidae. 
The Chiasmodontidae do not exhibit any muscle insertions on 
the dorsal-fin pterygiophores, whereas the Champsodontidae 
have a Type 1 condition very similar to that of scorpaenoids 
and serranids. Ammodytids, considered a derived trachinoid 
group, exhibit the primitive Type condition, while a puta- 
tive basal taxon, Cheimarrichthys, has Type 1, usually a 
derived morphology. Reversals are possible and structural 
homologies are uncertain (as discussed below), but the incon- 
sistencies among these taxa suggest a more thorough investi- 
gation of the composition of the Trachinoidei sensu Pietsch & 
Zabetian (1990) is warranted. 

There are differences even among those trachinoids that 
share a Type 2 morphology. Parapercis has a separate muscle 
that runs the entire length of the dorsal fin, with only 
intermittent epaxial fibres contributing to the muscle body. 
The posterior end of this separate muscle has some fibre and 
fascia connection with the supracarinalis posterior and only 
very weak attachments to the dorsal-fin pterygiophores that 
bear segmented rays. These pterygiophore insertions become 
strong anteriorly on spine-bearing pterygiophores, and the 
muscle is continuous with the supracarinalis anterior. This 
morphology is reminiscent of that of the Mullidae, described 
above, but shows an even closer association with the supra- 
carinalis muscles, suggesting a supracarinalis derivation, 
rather than an epaxial one, for these pterygiophore inser- 
tions. This is completely different from the condition in 



percophidids (Bembrops), which have a more typical Type 2 
morphology with epaxial insertions on to the five pterygio- 
phores of the anterior dorsal fin and to the first pterygiophore 
of the second, and with the anterior and posterior supracari- 
nalis muscles entirely separate from the epaxial musculature. 
Of course, such differences can be interpreted as autapomor- 
phies for families and genera among the trachinoids, but can 
also be considered suggestive of non-relationship. 

Epaxial/pterygiophore associations can also strengthen 
hypotheses about monophyly of currently recognized groups. 
Although not unique among perciforms, the occurrence of 
the Type 1 attachment in Niphon spinosus (Fig. 13) and its 
proposed relatives, the serranids, lends support to Johnson's 
(1983) placement of Niphon within this family based on other 
characters. Niphon had previously been aligned with the 
Percichthyidae, a family that exhibits Type epaxial mor- 
phology. 

Among blennioids (sensu Springer, 1993), the Type 1 
epaxial morphology has been found in all examined taxa, but 
there is some variation in details. Tripterygiids, dacty- 
loscopids, clinids, chaenopsids and blenniids have a separate, 
more-or-less fan-shaped, anterior slip of the epaxial muscle 
bundle that inserts on to the distal portions of the anterior 
dorsal-fin pterygiophores and extends forward to the skull 
(Fig. 14a-c). We have not found this anterior slip elsewhere 
among acanthomorphs with epaxial attachments to dorsal-fin 
pterygiophores, and interpret it as a synapomorphy of the 
Blennioidei. This corroborates Springer's (1993) hypoth- 
esized monophyly of the suborder. However, labrisomids are 
an exception among blennioids in exhibiting a more typical 
Type 1 morphology, without an anterior slip to the skull (Fig. 
14d). On the basis of molecular work, Stepien et al. (1993) 
hypothesized that the Labrisomidae are nested within the 
Blennioidei. Morphological characters provided by Springer 
(1993) also suggest that the Labrisomidae are not a basal 
blennioid family; for example, labrisomids, clinids, blenniids, 
and chaenopsids are more derived than tripterygiids and 
dactyloscopids in having the dorsalmost pectoral-fin ray 
articulating only with the dorsalmost proximal radial (vs with 
the scapula). Therefore, the absence of an anterior extension 
of the dorsal epaxial slip to the skull is most parsimoniously 
interpreted as a reversal, and a synapomorphy of the Labriso- 
midae. 

It is also possible that the discovery of epaxial/ 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



131 



,SCA 





EPAX 



Fig. 9 Type 2 epaxial musculature as exemplified by: a. Opistognathus maxilloxus (MPM 30098, 98.3 mm SL); b, Ronquilus jordani (MPM 
394, 133.1 mm SL). Abbreviations and other methods of presentation as in Figs 1, 3. Scale bars = 5 mm. 




Fig. 10 Epaxial insertions via long tendons of Sparisotna rubripinne (MPM 30040, 62.6 mm SL), typical of some Type 2 epaxial muscles. 
Abbreviations and other methods of presentation as in Figs 1 , 3. Scale bar = 5 mm. 




Fig. 11 Type 3 epaxial musculature as exemplified by Parupeneus multifasciatus (MPM 13530, 79.0 mm SL). In contrast to Types 1 and 2, 
the dorsal epaxial has direct fibre insertion to only one anterior pterygiophore, and ventral to the articulation with the spine. These anterior 
fibres merge with what is possibly a modified supracarinalis medius (SCM?), which has a similar anterior insertion and tendonous insertions 
to a few posterior pterygiophores more dorsally. The epaxial muscle shares only a few fibres with the supracarinalis medius near the 
posterior end of the first dorsal fin. The supracarinalis medius is contiuous with the supracarinalis posterior. SCM?, possible supracarinalis 
medius; other abbreviations and methods of presentation as in Figs 1, 3. Scale bar = 5 mm. 



pterygiophore morphologies could help to determine the 
relationships of some of the incertae sedis genera of the 
Percoidei as identified by Johnson (1984: table 119). For 
example, Siniperca has Type 2 musculature, which, although 
a relatively common morphology, does circumscribe a 
smaller perciform group from which possible relationships 
could be initially explored. Johnson (1984) suggested a rela- 
| tionship between Symphysanodon and Synagrops based on 
[larval morphology. We find the former taxon to have Type 
! and the latter to exhibit Type 2 epaxial morphologies. 
Although this does not refute a relationship, clearly more 
work needs to be done. Other orphan percoid genera such as 
Lateolabrax and Hapalogenys have Type morphology, 



which suggests they are unlikely to be included among Type 1 
taxa such as the Serranidae and Haemulidae (where each 
genus, respectively, had been traditionally placed). 

Many percoid families have not had their close relatives 
identified. Epaxial morphology might limit the search for 
possible relationships for some of these taxa. For example, 
the Pholidichthyidae exhibit Type 2 morphology, and their 
relationships might be narrowed to other taxa with this 
morphology. Gill & Mooi (1993) summarized evidence sug- 
gesting a possible relationship of the Notograptidae to acan- 
thoclinine plesiopids. Notograptids and some acanthoclinines 
share Type 2 morphology, which is absent in other plesiopids 
(Table 1), and this perhaps provides additional support for 



132 



R.D. MOOI AND AC. GILL 




a 




EPAX 



Fig. 12 Epaxial muscle morphology in: a, Lates niloticus (ROM 28524, 80.8 mm SL); b, Psammoperca waigiensis (ROM 46627, 91.2 mm 
SL). Note the insertions on to the second pterygiophore just ventral to the spine/pterygiophore articulation. Abbreviations and other 
methods of presentation as in Fig. 1. Scale bars = 5 mm. 




Fig. 13 Type 1 epaxial musculature in Niphon spinosus (USNM 59739, 128 mm SL). Note the separate slip of muscle inserting on to the 
second dorsal-fin pterygiophore and insertions to the 2nd through 8th pterygiophore, as in Epinephelus (Fig. 2). A separate bundle of fibres 
originates tendonously from the 10th pterygiophore to merge with those from the main epaxial muscle body. Abbreviations and other 
methods of presentation as in Fig. 1. Scale bar = 10 mm. 



their relationship, or at least does not contradict such a 
conclusion. 

Variation within families exhibiting a particular morpho- 
type has considerable potential for exploring internal rela- 
tionships. Among serranids, the anthiines Hypoplectrodes, 
Acanthistius , and Plectranthias all have very similar epaxial 
morphologies (Fig. 15), in which a short and not highly 
differentiated slip of muscle inserts on to the second pterygio- 
phore, and a weak tendon extends from the myoseptum to 
the first pterygiophore. This differs notably from the condi- 
tion in more typical anthiines, such as Pseudanthias , where a 
completely separate slip of epaxial muscle extends from 
below the fifth pterygiophore to insert on to the first through 
fourth pterygiophores (Fig. 16). These differences could 
provide evidence to unite members of one or another of these 
anthiine groups. If epinephelines are the sister group of 
anthiines as implied by Johnson (1988) and supported by 



Baldwin & Johnson (1993), decisions concerning homology 
and character definition become crucial; primitive epi- 
nephelines {Niphon, Epinephelus) have a separate slip of 
muscle inserting on to the second pterygiophore, but no weak 
tendon to the first pterygiophore, a combination of features 
found in the two anthiine groups (cf. Figs 2, 13, 15, 16). 

Variation in morphology of epaxial musculature might 
prove useful in other taxonomic groups. Insertion patterns of 
epaxial fibres to pterygiophores, the portions of the pterygio- 
phore involved in the insertion, the degree of separation of 
the involved musculature from the main body of the epaxial, 
and the relationship of the muscle with the supracarinalis all 
vary. Among the haemulids examined, Anisotremus has a 
limited number of attachments involving only the fourth and 
fifth pterygiophores, Conodon exhibits a more robust con- 
tinuous series of insertions extending from the third to 
seventh pterygiophores more typical of Type 1, and Haemu- 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



133 




Fig. 14 Epaxial musculature of blennioids: a, Tripterygiidae, 
Enneanectes pectoralis (MPM 22463, 26.5 mm SL), insertions to 
ninth pterygiophore; b, Chaenopsidae, Acanthemblemaria 
greenfieldi (MPM 24876, 30.4 mm SL), insertions to 13th 
pterygiophore; c, Blenniidae, Entomacrodus nigricans (MPM 
18256, 55.4 mm SL), insertions to 11th pterygiophore; d, 
Labrisomidae, Labrisomus bucciferus (MPM 31163, 57.0 mm SL), 
insertions to 13th pterygiophores. F, fan-shaped anterior slip of 
epaxial to skull; other abbreviations and methods of presentation 
as in Figs 1, 3. Scale bars = 1 mm (a,b), 5 mm (c,d). 



Ion has an almost completely separate series of muscle fibres 
that insert on to the third to ninth pterygiophores (Fig. 5). 
Type 1 appears to be the primitive condition for the cirrhi- 
toids (Fig. 17), with a secondary change to an epaxial/ 
pterygiophore association resembling more closely a Type 2 
morphology among some cirrhitids, which could be indicative 
of close relationship (Table 1). Among sciaenids both epaxial 
muscle Types and 2 occur, although their distributions are 
difficult to interpret with our current understanding of sci- 
aenid relationships (Table 1; Sasaki, 1989). Within scor- 
paenoids there is variation in epaxial morphology among the 
higher taxa. More extensive surveys within these and other 
groups with epaxial/pterygiophore insertions could help to 
elucidate some of their intrarelationships. 

Basal taxa (Embiotocidae, Pomacentridae, and Cichlidae) 
of the suborder Labroidei (Kaufman & Liem, 1982; Stiassny 
& Jensen, 1987) exhibits Type morphology, whereas some 
labrid taxa exhibit Type 2 (Table 1). It is most parsimonious 
to interpret Type 2 epaxial muscle as independently derived 
within labrids. This interpretation places Bodianus, Choero- 
don, and Tautoga as basal genera among the Labridae, and 
might be helpful for determining the polarization of other 
characters for phylogeny reconstruction in this confusing 
group. 

Some tetraodontiforms exhibit epaxial insertions on to the 
distal tips of the dorsal-fin pterygiophores that resemble Type 
2: Balistidae {Rhinecanthus , pers. obs.; probably Batistes, 
Balistapus, Melichthys, and Odonus from figs 78, 86, 88 and 
90 in Winterbottom, 1974b), Monacanthidae (Pervagor, pers. 
obs.; probably Aluterus, Cantherines, Chaetoderma, Paralu- 
teres, Paramonacanthus, and Stephanolepis from figs 100, 
102-105 and 108 in Winterbottom, 1974b), probably Tria- 
canthidae (Triacanthus , Tripodichthys, Trixiphichthys from 
figs 66, 76-77 in Winterbottom, 1974b), and perhaps some 
Triacanthodidae (Triacanthodes , Tydemania, and Mac- 
rorhamphosodes but not Hollardia or Parahollardia from figs 
49, 57-58, 61 and 64 in Winterbottom, 1974b). Consideration 
of the overall anterodorsal morphology of balistids, mona- 
canthids, and triacanthids suggests that these insertions are 
likely to have been derived independently of (and non- 
homologous with) those found in the Perciformes. In these 
tetraodontiforms, the anterior spinous dorsal fin is closely 
associated with the back of the skull and separated from the 
soft dorsal fin. It seems that the robust pterygiophores of the 
spinous dorsal fin act functionally as a supraoccipital crest 
and that the epaxial musculature inserts on to these elements 
as it would to such a crest. If triacanthodids, which possess a 
more conventional arrangement of spinous dorsal fin and 
posterior skull, do have epaxial/dorsal pterygiophore inser- 




Fig. 15 Type 1 epaxial musculature in Acanthistius sebastoides (USNM 246689, 96.5 mm SL). A weak tendon extends from a myoseptum to 
the first pterygiophore and a short and not highly differentiated muscle slip inserts on to the second pterygiophore. Abbreviations and other 
methods of presentation as in Fig. 1. Scale bar = 5 mm. 



134 



R.D. MOOI AND AC. GILL 




Fig. 16 Type 1 epaxial musculature in Pseudanthias taeniatus 
(USNM 279782, 44.8 mm SL). A separate slip of the epaxial 
inserts on to the first to fourth dorsal-fin pterygiophore, and 
epaxial insertions occur as far posteriorly as the eighth 
pterygiophore. Abbreviations and other methods of presentation 
as in Figs 1,3. Scale bar = 5 mm. 

tions, an argument could be made for homology with a Type 
2 morphology found among the perciforms, and implied 
relationships should be investigated. Optimizing epaxial char- 
acter distribution on existing phylogenies of the tetraodonti- 
forms (Winterbottom, 1974b; Leis, 1984) implies that the 
Type 2 morphology is the primitive condition for the order. 
Unfortunately, the character does not provide additional 
evidence for intrarelationships because the remaining extant 
families of tetraodontiforms do not possess a spinous dorsal 
fin. 

Even among taxa that do not exhibit epaxial insertions on 
to the distal portions of the proximal-middle pterygiophores 
or on to the distal radials, we did observe some possibly 
significant variation in other muscle morphology. As noted 
above, most (if not all) acanthomorphs have epaxial muscle 
insertions on to the proximal ends or along the shafts of the 
dorsal-fin pterygiophores. In most pleuronectiforms the 
epaxial muscle inserts via bundles of muscle fibres that pass 
underneath the depressores dorsales. Psettodes, usually con- 
sidered the sister group of other pleuronectiforms, has the 
epaxial muscles overlying most of the length of the pterygio- 
phores, with very short connections extending under the 
depressors to the pterygiophore shafts just ventral to the 
spine articulations. These connections only occur on the first 
12 pterygiophores. Psettodes is the only genus with dorsal-fin 
spines; all other flatfishes have epaxial insertions on to a 
higher number of pterygiophores, although most of the 
examined taxa have dorsal fins extending over the head. The 
extent to which the epaxials overlie the pterygiophores in 
remaining flatfishes varies considerably and might be of 
interest for determining relationships. The few examined 
bothids, paralichthyids and samarines have the epaxials cov- 
ering about half the length of the pterygiophores before short 
fibres attach to these bones. In available achirids the arrange- 
ment is similar to that described for bothids for the most 
posterior insertions, but anteriorly there are separate, elon- 
gate muscle slips that insert high on to the pterygiophore 
shafts just ventral to the ray articulations (Fig. 18). The 
cynoglossids, considered close relatives of the achirids (Chap- 
leau, 1993), have an epaxial morphology more similar to that 
of Psettodes in the one species examined. Poecilopsetta 
(Poecilopsettinae) has epaxial muscles that lie only as far 
dorsally as the proximal tips of the dorsal-fin pterygiophores, 
a condition that appears derived among pleuronectiforms and 
could provide evidence for relationship if observed in other 
taxa. Additional taxa need to be surveyed and character 
definitions must be clarified before epaxial morphology can 



contribute to an hypothesis of pleuronectiform phylogeny, 
but such an investigation appears worthy of pursuit. 

A similar, though less extensive, series of epaxial insertions 
under the depressors is found in Urophycis of the Gadidae 
(Fig. 19). Gadoids have not been thoroughly surveyed, but 
variation in epaxial muscle morphology, which is relatively 
simple to observe, might be useful for defining broad groups 
among gadoids, and paracanthopterygians in general. The 
occurrence of a Type 1 epaxial morphology among batra- 
choidids also suggests that a further survey of paracanthop- 
terygians could contribute to the understanding of 
relationships within this taxon. 

Of course, epaxial muscle morphology is not informative in 
all cases. For example, the Callionymoidei have a highly 
modified Type 2 condition consisting of a complex series of 
epaxial insertions on to the pterygiophores and modified 
neural spines. This will not help determine whether the 
Callionymoidei and Gobiesocidae are sister taxa, as hypoth- 
esized by Gosline (1970) and Winterbottom (1993: 409), 
because the latter taxon does not have a spine-bearing dorsal 
fin. It would be reasonable to suggest that any epaxial muscle 
associated with the fin would also have disappeared or have 
become reduced. Like any other feature, epaxial morphology 
can undergo secondary loss or autapomorphic modification. 

The homology of the three epaxial muscle morphotypes 
identified remains uncertain. It is unlikely that they form a 
nested set of character states. That a single morphotype can 
be independently derived from a Type condition is illus- 
trated by the independent development of Type 2 in some 
labrids, and similarly in the Acanthoclininae, a derived taxon 
within the Plesiopidae which otherwise exhibit Type (Table 
1). The occurrence of a Type 1 morphology in some paracan- 
thopterygians, usually considered unrelated to perciforms, 
also indicates non-homology of the character state as recog- 
nized here. These examples suggest that the morphologies 
themselves require better definition. With more sophisticated 
inquiry through ontogenetic or neurological studies, it is 
possible that these cases of non-homology can be dismissed as 
inappropriately recognized character state equivalence. In 
the apparently unique morphology of the Mullidae, Type 3, 
the pterygiophore insertions involve both epaxial and supra- 
carinalis fibres (Fig. 11). The muscle is essentially separate 
from the main epaxial muscle body over its entire length, a 
condition very different from that found in the Type 1 or 2 
morphologies. It appears that the Type 3 musculature is 
directly derived from the supracarinalis muscles, rather than 
from the epaxial muscles. This also seems likely in the 
pinguipedid trachinoid Parapercis, where the muscle bundle 
inserting on to the dorsal-fin pterygiophores is continuous 
with the supracarinalis anterior and posterior. The condition 
in mullids and Parapercis could provide evidence that, in at 
least these taxa, the sheet of muscle inserting on to dorsal-fin 
pterygiophores is actually derived from the supracarinalis, 
and only secondarily shares muscle fibres from the epaxialis. 
These problems of homology and ontogeny of the muscle are 
beyond the scope of this paper. 

Despite these concerns, we are confident that epaxial 
morphology is useful for exploring the relationships of acan- 
thomorph taxa. Of course, this one character complex must 
be taken in the context of other characters before any 
definitive statements can be made regarding, for example, 
percoid/scorpaenoid relationships, or before making gener- 
alizations concerning the integrity of such groups as the 
trachinoids. However, one important concept that the inves- 



EPAXIAL MUSCLES AND ACANTHOMORPH RELATIONSHIPS 



135 




SP1 




Fig. 17 Epaxial musculature in cirrhitoids: a. Type 1 in Aplodactylidae, Aplodactylus punctatus (USNM 227298, 58.0 mm SL); b, modified 
Type 1 in Cirrhitidae, Paracirrhitus arcatus (MPM 13587, 66.7 mm SL); c, Type 2 in Cirrhitidae, Amblycirrhitus bimacula (MPM 13509, 
56.9 mm SL). Abbreviations and other methods of presentation as in Figs 1, 3. Scale bars = 5 mm. 




T ig. 18 Epaxial musculature of the pleuronectiform Achirus linealus (MPM 13783, 95.0 mm SL). Individual slips of epaxialis insert on to the 
dorsal third of the dorsal-fin pterygiophore shafts under the depressores dorsales. Abbreviations and other methods of presentation as in 
Fig. 1. Scale bar = 10 mm. 



136 



R.D. MOOI AND AC. GILL 




EPAX 



Fig. 19 Epaxial musculature in the gadid Urophycis regia (MPM 
31175, 133.0 mm SL). Individual slips of muscle extend from the 
main epaxialis body to insert on the dorsal-fin pterygiophore 
shafts under the depressores dorsales. Abbreviations and other 
methods of presentation as in Figs 1, 3. Scale bars = 5 mm. 

tigation of epaxial muscle variation elucidates is the need to 
shrug off the strait jacket of present classifications when 
investigating phylogeny of higher taxa. This is particularly 
true when the taxa are already recognized as non- 
monophyletic, undefined, or poorly defined (e.g., Percoidei, 
Perciformes, Paracanthopterygii), but have in essence been 
reified over time. It is necessary to look beyond the tradi- 
tional taxonomic boundaries, not only when dealing with 
undefined groups such as the percoids, but also when investi- 
gating apparently well-defined or well-established taxa such 
as the scorpaenoids and trachinoids. Epaxial muscle inser- 
tions to dorsal-fin pterygiophores provide one character 
complex that illustrates the potential and novel relationships 
that such an approach can suggest. These possible relation- 
ships await rejection or corroboration from similar studies of 
additional characters. 



Acknowledgements. Specimens were kindly made available by: 
Mary Anne Rogers, Kevin Swagel, Mark Westneat (FMNH), Tony 
Harold, Marty Rouse, Rick Winterbottom (ROM), Susan Jewett, 
Lisa Palmer, Dave Johnson (USNM), Norma Feinberg, Melanie 
Stiassny (AMNH), Mark McGrouther, Sally Reader, Tom Trnski 
(AMS), Oliver Crimmen, Anne-Marie Hodges (BMNH). Earlier 
drafts of this manuscript were reviewed by the late Humphry 
Greenwood, Dave Johnson, Jeff Leis, Nigel Merrett, Colin Patter- 
son, Darrell Siebert and Vic Springer; their comments were greatly 
appreciated. This material is based upon work supported by Smithso- 
nian postdoctoral fellowships (RDM, ACG), a Lerner-Gray 
Research Fellowship at the American Museum of Natural History 
(ACG), and the National Science Foundation under Grant No. 
DEB-9317695 (RDM). 

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206-292. (ii) Books: Jeon, K.W. 1973. The Biology of 
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Articles from books: Hartman, W.D. 1981. Form and distri- 
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CONTENTS 



91 Preliminary studies on a mandibulohyoid 'ligament' and other intrabuccal connective tissue 

linkages in cirrhitid, latrid and cheilodactylid fishes (Perciformes: Cirrhitoidei) 

P.H. Greenwood 
103 A new species of Crocidura (Insectivora: Soricidae) recovered from owl pellets in Thailand 

P.D. Jenkins and A.L. Smith 
111 Redescription of Sudanonautes floweri (De Man, 1901) (Brachyura: Potamoidea: Potamo- 

nautidae) from Nigeria and Central Africa 

N. Cumberlidge 
121 Association of epaxial musculature with dorsal-fin pterygiophores in acanthomorph fishes, 

and its phylogenetic significance 

R.D. MooiandA.C. Gill 



J atural Hi; 
ZOOLOGY SERIES 

Vol. 61, No. 2, November 1995